North Korea has pledged to send military personnel to Ukraine within a month to support Putin's war-weary forces as both sides struggle to make a decisive breakthrough.
Pyongyang will take an unprecedented step in sending construction and engineering forces to occupied territories of Ukraine as early as July to assist in rebuilding work, South Korea's TV Chosun reported earlier, citing a government official.
The rare vow of foreign support follows president Vladimir Putin's official state visit to North Korea earlier this month - the first in almost a quarter of a century - which culminated in the signing of a so-called defence pact on June 19.
The treaty binds its signatories to providing 'military and other assistance with all means in its possession without delay' should either find itself 'put in a state of war by an armed invasion'.
North Korea is believed to have already supplied Russia with about 1.6mn artillery shells between August and January as Moscow continues to hammer populated areas of Ukraine and tries to make decisive gains in the north.
As polarisation hardens, Pyongyang officials criticised the United States on Monday for its expanding military assistance to Ukraine and dispatch of an aircraft carrier to South Korea, warning it could provoke a 'new world war', according to state media.
ARussian tank fires at Ukrainian troops from a position near the border with Ukraine in Belgorod in a photo shared by the Russian Defence Ministry on March 19
Rescuers clear the rubble of a destroyed residential building following a missile attack in Lugansk, Russian-controlled Ukraine, on June 7
Just days after Russian President Vladimir Putin's visit to Pyongyang, Pak Jong Chon, one of North Korea's top military officials, said Moscow the 'right to opt for any kind of retaliatory strike' if Washington kept pushing Ukraine to a 'proxy war' against Russia.
It could provoke a stronger response from Moscow, and a 'new world war', Pak said, according to KCNA.
He referred to comments by the Pentagon last week that Ukrainian forces can use U.S.-supplied weapons to strike Russian forces anywhere across the border into Russia.
North Korea's vice minister of defence, Kim Kang Il, said the arrival of an American aircraft carrier in South Korean waters was a 'very dangerous' show of force, leaving doors open for North Korea's 'overwhelming, new demonstration of deterrence,' state media KCNA reported.
The Theodore Roosevelt aircraft carrier - a colossal vessel measuring 1,092ft - arrived in the South Korean port city of Busan on Saturday to take part in joint military exercises later this month with the host nation and Japan, US naval officials said.
Washington and Seoul have been increasingly alarmed by deepening military cooperation between Russia and the North, and have accused them of violating international laws by trading in arms for Russia to use against Ukraine. Moscow and Pyongyang have denied any arms transfer.
The pact signed by Putin and North Korean leader Kim Jong Un during the Russian president's visit to Pyongyang last week commits each side to provide immediate military assistance to the other in the event of armed aggression against either one of them.
Putin thanked Kim for his hospitality during the trip which brought ties to an unprecedented level, the Kremlin said on Monday.
Analysts say the pact would lay the framework for arms trade between the two countries and facilitate their anti-U.S. and anti-West coalition.
Senior officials of South Korea, the U.S. and Japan condemned 'in the strongest possible terms' deepening military cooperation between North Korea and Russia in a joint statement released by Seoul's foreign ministry on Monday.
South Korea now expects the North to dispatch a large-scale engineering force to occupied Donetsk Oblast as early as next month to help rebuild infrastructure in Donetsk City.
The North reportedly operated 10 engineering brigades, according to the ISW.
Putin has tried to downplay the possibility of North Korean troops serving alongside Russia's in Ukraine, however.
The Russian president also visited Vietnam this month in an apparent bid to shore up ties with its ally, a significant buyer of Russian arms.
Analysts believe Moscow is now trying to establish a bloc of friendly states with links to the former USSR as Ukraine finds backing in NATO and Western allies.
Russia also made waves signing a memorandum regarding the supply of Russian gas into Iran - a boon for Moscow amid sanctions and reported disagreements between Russian and China over the Russian supply of gas.
Kim Jong Un (R) and Russia's President Vladimir Putin (L) shaking hands after a signing ceremony following their bilateral talks on June 19
AUkrainian tank of the 17th tank brigade fires at the Russian positions in Chasiv Yar, Feb 29
Russia may have received about 1.6 million artillery shells from North Korea from August to January, the Washington Post reported on Saturday, analysing data from U.S. security nonprofit C4ADS that shows 74,000 metric tons of explosives moved from Russia's far east ports to other sites mainly along the borders near Ukraine.
North Korea plans to send construction and engineering forces to Russia-occupied territories of Ukraine as early as next month for rebuilding work, South Korean cable TV network TV Chosun reported earlier, citing a South Korean government official.
Those forces, working overseas under the disguise of construction workers to earn hard currency for the regime, would be moved from China to those Russia-held regions, the network said.
Asked about the TV Chosun reports, South Korea's foreign ministry said it was continuing monitoring the situation.
