North Korea will back Russia until it achieves victory in Ukraine, Foreign Minister Choe Son Hui said in Moscow as the United States warned thousands of Pyongyang’s troops were at the Ukrainian border and could soon be deployed into combat.

In her meeting on Friday with Russian Foreign Minister Sergey Lavrov, Choe also accused the US and South Korea of plotting a nuclear strike against her country.

“Our traditional, historically friendly relations, which have travelled the tested path of history, today … are rising to a new level of relations of invincible military comradeship,” she said, praising the role played in this by North Korean leader Kim Jong Un and Russian President Vladimir Putin.

She said North Korea had no doubt that under Putin’s “wise leadership” the Russian army and people would “achieve a great victory in their sacred struggle to protect the sovereign rights and security interests of their state”.

“And we also assure that until the day of victory we will firmly stand alongside our Russian comrades,” Choe said.

Lavrov spoke of the “very close ties” between the two countries’ militaries and said this enabled them to solve important security tasks together.

The two did not address statements by leaders in Ukraine, South Korea and their Western allies that Pyongyang had deployed some 10,000 North Korean soldiers to Russia to fight in Ukraine.

On Thursday, US Secretary of State Antony Blinken said as many as 8,000 North Korean soldiers were in the Kursk region, where Ukrainian troops crossed the border into Russia in a surprise incursion in August, and that he expected them to go into combat against Ukraine in the coming days.

“We are deeply grateful to our Korean friends for their principled position regarding the events that have now unfolded in Ukraine as a result of the West’s course of advancing NATO to the east and encouraging an openly racist regime to exterminate everything Russian,” Lavrov said.

Choe told Lavrov that the situation on the Korean Peninsula could become “explosive” any moment, given the threats from Washington and Seoul, but did not provide any evidence to back her allegations.

She said North Korea needed to strengthen its nuclear arsenal and perfect its readiness to deliver a retaliatory nuclear strike if necessary.

On Thursday, Pyongyang confirmed it launched a new intercontinental ballistic missile (ICBM) towards waters off its eastern coast in what was the longest flight time yet for a North Korean missile, authorities in South Korea and Japan said, raising fears of advanced weapons development by the reclusive nation.

Kim was present at the missile test launch and issued a warning to his enemies as he described it as an expression of his country’s resolve to respond to external threats to North Korea’s security, the official Korean Central News Agency (KCNA) reported.

On Friday, North Korea boasted that the ICBM it test-launched was “the world’s strongest missile” and identified it as Hwasong-19.