President Vladimir Putin said on Thursday that South Korea would be making "a big mistake" if it decides to supply arms to Ukraine and that Moscow would respond to such a move in a way that would be painful for Seoul.
Putin, who was speaking at a news conference in Vietnam, was reacting to a report from Yonhap news earlier on Thursday which said South Korea would review the possibility of supplying weapons to Ukraine after Putin and North Korean leader Kim Jong-un signed a mutual defence pact a day earlier.
Putin said Seoul had nothing to worry about when it came to the pact between Moscow and North Korea.
"South Korea, the Republic of Korea has nothing to worry about because our military assistance under the treaty we signed only arises if aggression is carried out against one of the signatories. As far as I know, the Republic of Korea is not planning aggression against the DPRK (North Korea," Putin told reporters.
He warned Seoul against moving to supply weapons to Kyiv.
"As for the supply of lethal weapons to the war zone in Ukraine, that would be a very big mistake," he said.
"I hope that this will not happen. And if it does happen, then we will also take appropriate decisions, which are unlikely to please the current leadership of South Korea," said Putin.
The Russian leader was speaking to reporters in Vietnam at the end of a two-day trip to Asia. He held talks in North Korea a day earlier.