Russian lawmakers will vote Wednesday to ratify a landmark mutual defence pact with North Korea, as the West says Pyongyang sent thousands of troops to fight for Russia against Ukraine.
The agreement formalises months of deepening security cooperation between the two nations who were Communist allies throughout the Cold War.
North Korea has become one of the most vocal and important backers of Russia's full-scale offensive on Ukraine.
The West has long accused Pyongyang of supplying artillery shells and missiles to Moscow to fire on Ukraine.
The latest accusations, based on intelligence reports, that North Korea has deployed around 10,000 troops to Russia suggest even deeper involvement in the conflict and have triggered an outcry and warnings in Seoul, Kyiv and Western capitals.
Under the strategic partnership treaty between Russia and North Korea, each country would be obligated to provide military assistance "without delay" if the other were invaded, their leaders said when signing it in June.
"It is really a breakthrough document," Russian President Vladimir Putin said at a news conference in the North Korean capital.
He added that it provided, "among other things, for mutual assistance in case of aggression against one of the parties to this treaty".
It also commits them to cooperate internationally to oppose Western sanctions and coordinate positions at the United Nations.
Putin signed the deal in June during his first trip in 24 years to North Korea, where he was welcomed by leader Kim Jong Un in a lavish ceremony.
Kim has called Putin his "closest comrade" while Foreign Minister Choe Son Hui said last week that North Korea would "stand firmly by our Russian comrades until victory day".
She called Moscow's offensive against Ukraine a "sacred struggle" and said Pyongyang believed in Putin's "wise leadership".
Russia's Federation Council, the upper chamber of a rubber-stamp parliament, is set to approve the treaty.
It will then go back to Putin's desk for a final signature.
The ratification comes as North Korea faces growing international pressure not to send its troops into combat alongside Russia.
South Korea warned Tuesday that a substantial deployment was already near the combat zone, including in Russia's western Kursk region, where Kyiv has been mounting a cross-border offensive since the summer.
"More than 10,000 North Korean soldiers are currently in Russia, and we assess that a significant portion of them are deployed to frontline areas, including Kursk," Jeon Ha-gyu, a spokesman for the South Korean Defence Ministry, said Tuesday.
North Korea has denied the deployment.
Asked directly about the reports last month, Putin did not deny that North Korean troops had been sent to Russia.
And several other Russian officials have deflected requests to comment on Western intelligence.
"The Kyiv regime is trying to do everything to involve Seoul" in the conflict, Kremlin spokesman Dmitry Peskov told reporters on Tuesday, refusing to comment on the substance of the allegations.
In exchange for sending troops, the West fears Russia is offering North Korea technological support that could advance Pyongyang's nuclear weapons programme.
The reclusive state fired a salvo of short-range ballistic missiles early Tuesday, Seoul's military said, its second launch in days.
But sending North Korean troops to fight against Ukraine would be a major escalation in the conflict, more than two and a half years after Moscow launched its full-scale offensive.
Russia has seized the momentum on the battlefield this year as it grinds through the eastern Donbas region, capturing a string of towns and villages as Ukraine struggles with manpower and ammunition shortages.
Moscow's forces took control of more territory in October than in any single month since March 2022, AFP analysis of data compiled by the Institute for the Study of War (ISW) showed.
Ukrainian President Volodymyr Zelensky has become increasingly exasperated at what he calls the West's delays in giving Ukraine the firepower it needs to push Russia back and over a lack of response to reports of the North Korean troop deployment.
