This is CNBC's live blog tracking developments on the war in Ukraine. See below for the latest updates. 

The Kremlin confirmed that North Korea's leader Kim Jong Un arrived in Russia's Far East on Tuesday morning, and dismissed Washington's warnings about Russian President Vladimir Putin's forthcoming meeting with Kim.

Kim travelled to Russia on an armored train for a one-to-one meeting with Putin which could take place today or tomorrow. The location of the meeting has not been revealed. Kim arrived in Vladivostok, where the the Eastern Economic Forum is taking place this week. Vladivostok, on Russia's Pacific coast, lies around 80 miles from Russia's border with North Korea.

The White House has warned that arms negotiations between North Korea and Russia have been "actively advancing" in recent weeks, saying Moscow aims to buy weaponry from Pyongyang for use in the Ukraine war. Russia and North Korea deny those claims.

The U.S. repeated warnings to North Korea on Monday not to send arms to Russia, reiterating that any arms deal or military support for Russia's war in Ukraine would directly violate a number of U.N. Security Council resolutions, such as the prohibition of all weapons trade with the country. It said it's ready to impose more sanctions against North Korea if there is a deal.

Kremlin Press Secretary Dmitry Peskov dismissed the U.S.' warnings, however, telling reporters that Moscow and Pyongyang are not interested in "warnings from Washington."

'Sham elections' won't alter G7 support for Ukraine, ministers say

The foreign ministers making up the G7 said in a joint statement that Russian-instigated elections in occupied areas of Ukraine would not impact the countries' support for Kyiv.

"Russia's attempt to create a situation of fait-accompli through these sham 'elections' will not alter our approach nor our support to Ukraine as it fights to reclaim its internationally-recognized territory," the statement said.

"We will stand with the Ukrainian people and continue to provide the financial, humanitarian, security and diplomatic support Ukraine requires for as long as it takes."

The comments come after G7 leaders, comprising Canada, France, Germany, Italy, Japan, the U.K. and the U.S. came together at the G20 summit in New Delhi on Sept. 9 and 10.

— Hannah Ward-Glenton

Pictures show Kim Jong Un's arrival in Russia

Pictures have emerged of North Korean leader Kim Jong Un's arrival in Russia after he traveled by train to speak with Russian President Vladimir Putin.

The leader of North Korea arrived in Russia earlier Tuesday, according to Russian state media reports.

It was reported by the Associated Press that Kim Jong Un met with Russian Minister of Natural Resources and Ecology Alexander Kozlov upon his arrival in Khasan, which is around 79 miles (127 kilometers) south of Vladivostok and lies on the border between Russia and North Korea.

The photos were released by the governor of the Russian far eastern region of Primorsky Krai, Oleg Kozhemyako, via Telegram, AP reported.

— Hannah Ward-Glenton

Germany wants to encourage partners to boost Ukraine's air defenses, foreign minister says

German Foreign Minister Annalena Baerbock said Berlin would encourage partners to deliver any available air defense systems to Ukraine ahead of winter, speaking in an interview with newspaper Frankfurter Allgemeine Zeitung, as translated by CNBC.

"We have to build a winter shield of air defense systems across Ukraine's critical infrastructure," Baerbock told FAZ.

Baerbock said Germany would be making more IRIS-T missiles available to Ukraine in the coming months.

Germany's foreign minister visited Kyiv Monday and said that while Ukraine's place was in the European Union, more needed to be done to tackle corruption in the country.

— Hannah Ward-Glenton

Russia's natural resources minister reportedly meets North Korea's Kim Jong Un

Russia's natural resources minister on Tuesday said they met with Kim Jong Un, Reuters reported, citing state media outlet RIA.

Russian President Vladimir Putin is expected to hold talks with the North Korean leader after he arrived in Russia earlier in the day, but details as to when the pair will speak, and the exact nature of the discussions, remain unclear.

— Hannah Ward-Glenton

When and where will Kim and Putin meet? Here's what we know

North Korean Kim Jong Un's visit to Russia has been shrouded in a lot of secrecy. That's not a surprise for the infamously reclusive and paranoid leader who rarely leaves the country.

Indeed, this is Kim's first known trip abroad in the last four years, and Kim arrived Tuesday morning on his armored train in Vladivostok with an entourage including officials from the Workers' Party of Korea (the only and ruling party of North Korea), government and armed forces, according to domestic media.

As for exactly where and when Kim will meet Russian President Vladimir Putin, the Kremlin is tight-lipped.

Asked by reporters when the one-to-one meeting between the leaders would take place, Putin's Press Secretary Dmitry Peskov told reporters that it would be "in the coming days," without specifying the date.

He also did not specify the location, saying: "No, I won't tell you yet," news agency Interfax reported.

There will be at least one extra participant in the Russian delegation: Defense Minister Sergei Shoigu. The senior official is no stranger to Kim, having met him during a trip to North Korea in July.

Then, Kim personally gave Shoigu a tour of Pyongyang's latest missiles including the Hwasong-18 intercontinental ballistic missile (ICBM), the state's first ICBM to use solid propellants, which can enable faster and easier deployment of missiles during war, Reuters noted, saying that the missile was first flown in April.

— Holly Ellyatt

Sweden to consider sending fighter jets to Ukraine, media reports

The Swedish government will ask its armed forces to investigate the potential for sending Gripen fighter jets to Ukraine, Swedish public radio (SR) reported on Tuesday, citing unnamed sources.

The government wants to know, among other things, how a handover would affect Sweden's defence capabilities and how quickly Sweden could get new Gripen fighters, SR reported.

The government may make a formal request to the armed forces as early as Thursday to officially consider the issue, Swedish Radio said.

According to the SR report, Ukraine has expressed hope of receiving one division, consisting of between 16 and 18 of the Swedish-made jets, which are produced by defence contractor Saab.

— Reuters

Russian defense minister to take part in Putin-Kim talks

Russian Defense Minister Sergei Shoigu will participate in negotiations between North Korean leader Kim Jong Un and Russian President Vladimir Putin, the Russian president's press secretary Dmitry Peskov said Tuesday.

A separate meeting of Russian and North Korean defense ministers is not expected during the visit of the country's leader Kim Jong-un to Russia, Peskov added, RIA Novosti reported.

The presence of Shoigu is bound to fuel Western concern that the talks between Putin and Kim will focus on North Korea giving weaponry to Russia in return for food and financial aid, and possibly, military technology. Russia and North Korea insist they have not discussed arms deals.

— Holly Ellyatt

The West is worried about what Russia and North Korea are planning

As the leaders of North Korea and Russia prepare to meet in Russia's Far East, deepening military, economic and geopolitical cooperation is on the official agenda.

Behind closed doors, however, White House officials and political analysts believe the talks between Kim Yong Un and Vladimir Putin will focus on arms deals and military cooperation that could potentially take their relationship to another, more disconcerting, level.

There are concerns that Pyongyang could provide weaponry to Russia for use in its war in Ukraine, including millions of artillery shells, rockets, anti-tank missiles and small arms ammunition. There are also fears about what Moscow might offer the economically isolated and heavily sanctioned North Korea in return.

Any deal between the two powers is expected to go beyond weaponry, with experts noting that this burgeoning "transactional" relationship could see advanced military technology and intelligence shared with Pyongyang — which could enable it to further that nuclear program and weapons of mass destruction.

Russia and North Korea continue to deny any arms deals have taken place and the Kremlin said Tuesday morning that it's not interested in Washington's warnings over the forthcoming meeting.

Experts say there's little the West can do to stop Russia and North Korea making "life difficult for the U.S. and its partners" given that it has "few efficacious tools with which to respond to the emerging axis."

Read more on the story here: With Putin and Kim Jong Un set to meet, the West fears what Russia and North Korea are planning

— Holly Ellyatt

Putin says up to 1,500 soldiers are signing up each day

President Vladimir Putin said on Tuesday that 1,000 - 1,500 Russians were signing voluntary contracts to join the military every day.

Putin was responding to a question about whether Russia needed to introduce a new compulsory mobilisation to boost its military effort in Ukraine, something the Kremlin has repeatedly said is not necessary.

Over the past six or seven months, 270,000 people have signed voluntary contracts, Putin said - a figure slightly lower than the 280,000 that former president Dmitry Medvedev stated earlier this month.

Putin also said on Tuesday he thought that Ukraine might only be ready to discuss peace when it ran out of resources but that Kyiv would use a potential cessation of hostilities to rearm.

Speaking at a forum in Russia's far eastern city of Vladivostok, Putin repeated his assertion that Ukraine's ongoing counteroffensive had failed, saying it had borne "no results".

— Reuters

Humanitarian aid for North Korea likely to be a topic for Putin and Kim

Humanitarian aid will be a topic that Russian President Vladimir Putin and North Korean leader Kim Jong Un discuss in their forthcoming one-to-one meeting, a senior Russian official said Tuesday.

Russian Deputy Foreign Minister Andrei Rudenko said the issue of Russia providing humanitarian aid to Pyongyang will be discussed.

He noted that "all issues can be discussed" but that any humanitarian aid for Pyongyang would be among them, particularly given that such aid is exempted from U.N. sanctions.

"There are restrictions, but not on food. I will not predict the results, but since many representatives of our government are there, the issues will be discussed as a whole," Rudenko told reporters on the sidelines of the Eastern Economic Forum, news agency RIA Novosti reported.

North Korea is an economically and geopolitically isolated country that has had numerous sanctions imposed on it for its prohibited nuclear weapons program and testing.

The country's poor economic infrastructure and food production, closed border and prioritization of the military sector have led to food shortages and famine.

— Holly Ellyatt

Kremlin dismisses U.S. warnings over meeting with North Korea

Russia dismissed warnings from the White House on Monday that any arms deal between Moscow and North Korea would trigger immediate further sanctions.

The White House has warned in recent weeks that arms negotiations between North Korea and Russia have been "actively advancing," saying Moscow aims to buy weaponry from Pyongyang for use in the Ukraine war.

U.S. officials are sure that those arms talks will continue when North Korea's leader Kim Jong Un and Russian President Vladimir Putin meet in the coming days in Vladivostok in Russia's Far East.

The U.S. repeated warnings to North Korea on Monday not to send arms to Russia, reiterating that any arms deal or military support for Russia's war in Ukraine would directly violate a number of U.N. Security Council resolutions, such as the prohibition of all weapons trade with the country. It said it's ready to impose more sanctions against North Korea if there is a deal.

The Kremlin's Press Secretary Dmitry Peskov dismissed the U.S.' warnings, however, telling reporters that Moscow and Pyongyang are guided by the interests of bilateral relations and are not interested in "warnings from Washington," state news agency Tass reported Tuesday.

"As you know, after all, realizing our relations with our neighbors, including North Korea, the interests of our two countries are important for us, and not warnings from Washington. It is the interests of our two countries that we will focus on," Peskov said.

He noted that the Russian Federation is ready, if necessary, to discuss with the DPRK issues related to the sanctions of the UN Security Council."

Peskov said the leaders would discuss issues of bilateral cooperation between Russia and Pyongyang as well as international affairs and "sensitive areas," without giving further detail.

"First of all, of course, issues related to bilateral relations, bilateral cooperation, trade and economic ties, cultural exchanges will be discussed. Of course, there will be a rich exchange of views on the situation in the region and on international affairs in general, because this is of interest both to Putin and to our guest from Pyongyang," Tass reported Peskov as saying.

— Holly Ellyatt

North Korea's Kim Jong Un has arrived in Russia, Kremlin confirms

North Korean leader Kim Jong Un arrived in Russia's Far East on Tuesday morning, the Kremlin confirmed Tuesday.

Kremlin Press Secretary Dmitry Peskov confirmed the arrival, Interfax news agency reported.

Kim travelled to Russia on an armored train for a one-to-one meeting with Russian President Vladimir Putin which could take place today or tomorrow. The location of the meeting has not been revealed. That comes as the Eastern Economic Forum takes place in Vladivostok, 80 miles from Russia's border with North Korea.

The Rossiya-1 TV channel showed footage of Kim's train arriving after a journey shrouded in secrecy. Interfax news agency reported that the train crossed the Khasan station, on the border with North Korea, in "an atmosphere of absolute secrecy" on Tuesday morning.

Kim left for Russia by train on Sunday, the North Korean news agency KCNA reported, adding that representatives of the ruling Workers' Party of Korea, as well as North Korean military leaders, are also traveling to Russia with Kim.

The two leaders are expected to discuss bilateral cooperation as well as arms, Western intelligence claims, as Russia looks to its allies for military equipment to prosecute its war in Ukraine. North Korea and Russia deny the claims.

— Holly Ellyatt

U.S. won't hesitate to impose sanctions if North Korea sends Russia weapons

The U.S. is set to impose new sanctions against North Korea if the country ships arms to Russia, a State Department spokesperson said Monday.

Any shipment of weapons from North Korea to Russia would violate multiple U.N. Security Council resolutions, State Department spokesperson Matthew Miller said during a briefing.

"We of course have aggressively enforced our sanctions against entities that fund Russia's war effort and we will continue to enforce those sanctions and will not hesitate to impose new sanctions, if appropriate," Miller said.

"We have always looked to impose sanctions and hold accountable countries or entities that support Russia's war effort," he said.

The U.S. warning comes as North Korean dictator Kim Jong Un is set to visit Russia this week. North Korean state media said Kim will meet with Russian President Vladimir Putin during his visit.

U.S. officials say Pyongyang and Moscow have discussed a potential arms deal and those talks may continue when Kim visits Russia.

"We are going to monitor very closely the outcome of this meeting," Miller said.

-- Spencer Kimball

White House urges North Korea to not provide arms to Russia

A spokesperson from the U.S. National Security Council urged North Korea to hold up its agreement to not sell or provide arms to Russia as North Korean leader Kim Jong Un reportedly travels to the country.

"As we have warned publicly, arms discussions between Russia and the DPRK are expected to continue during Kim Jong-Un's trip to Russia. We urge the DPRK to abide by the public commitments that Pyongyang has made to not provide or sell arms to Russia," NSC Spokesperson Adrienne Watson said in a statement, as reported by NBC News.

The Council has already said it is "concerned" about arms discussions between North Korea and Russia, with John Kirby, assistant to the Secretary of Defense for Public Affairs, having said on Aug. 30 that new information suggested arms negotiations between the two countries were "actively advancing."

— Hannah Ward-Glenton

Kremlin confirms North Korea's leader Kim Jong Un is to visit Russia

The Kremlin said that North Korea's leader Kim Jong Un will visit Russia this week, having previously denied any meeting would take place.

Speculation had been mounting that a meeting between Kim and Putin would take place on the sidelines of the Eastern Economic Forum in Vladivostok.

Pyongyang and the Kremlin had denied this, with Kremlin spokesman Dmitry Peskov saying earlier this morning that there were no plans for a meeting.

A few hours later, however, the Kremlin issued a statement saying: "At the invitation of the President of the Russian Federation Vladimir Putin, Chairman of State Affairs of the Democratic People's Republic of Korea Kim Jong-un will pay an official visit to the Russian Federation in the coming days."

Russian news outlet RBC reported an unnamed Russian official as telling it that the meeting would take place on Sept. 13. Earlier, South Korean media reported that a North Korean train, presumably carrying Kim, had left for Russia.

White House officials believe arms negotiations are "actively advancing" between the countries, and will continue when Putin and Kim meet. Russia and North Korea have rejected those claims.

 — Holly Ellyatt

North Korean train presumably carrying leader Kim Jong Un departed for Russia, media reports

A North Korean train presumably carrying North Korean leader Kim Jong Un has departed for Russia for a possible meeting with Russian President Vladimir Putin, South Korean media said Monday.

Citing unidentified South Korean government sources, the Chosun Ilbo newspaper reported that the train likely left the North Korean capital of Pyongyang on Sunday evening and that a Kim-Putin meeting is possible as early as Tuesday.

The Yonhap news agency and some other media published similar reports. South Korea's National Intelligence Service didn't immediately confirm those details.

U.S. officials released intelligence last week that North Korea and Russia were arranging a meeting between their leaders that would take place within this month as they expand their cooperation in the face of deepening confrontations with the United States.

According to U.S. officials, Putin could focus on securing more supplies of North Korean artillery and other ammunition to refill draining reserves and put further pressure on the West to pursue negotiations amid concerns about a protracted conflict in Ukraine.

In exchange, Kim could seek badly needed energy and food aid and advanced weapons technologies, including those related to intercontinental ballistic missiles, nuclear-capable ballistic missile submarines and military reconnaissance satellites, analysts say.

There are concerns that potential Russian technology transfers would increase the threat posed by Kim's growing arsenal of nuclear weapons and missiles that are designed to target the United States, South Korea, and Japan.

— Associated Press

Read CNBC's previous live coverage here:

North Korea's Kim Jong Un reportedly on train to Russia as Kremlin confirms visit is happening