South Korea said it might send weapons to Ukraine after Putin signed a security pact with its biggest enemy

• South Korea said it could start sending weapons to Ukraine.
• It came after Russia signed a security pact with North Korea.

South Korea said it could send weapons to Ukraine after Russia signed a security pact with Seoul's biggest regional foe, North Korea.

"We will reconsider the issue of supplying weapons to Ukraine," South Korean national security advisor Chang Ho-jin told reporters late on Thursday after the Russian President signed the pact with North Korean leader Kim Jong Un in Pyongyang.

"Any cooperation that helps increase North Korea's military power is a violation of the UN Security Council," Chang added. "It doesn't make sense to promise military co-operation, assuming a pre-strike by the international community that will not happen."

Putin became the first Russian leader to visit North Korea in a quarter of a century this week, cementing an alliance with the pariah state.

The partnership has seen North Korea supply Russia with badly needed artillery for its war in Ukraine. In exchange, reports say, Russia has provided North Korea with satellite technology.

The security pact signed by the leaders, in which they pledged to provide each other with military support in a conflict, has spiked tensions in East Asia, where North Korea has long menaced US regional allies South Korea and Japan with an attack.

North Korea is under international sanctions to curtail its nuclear weapons program, and though Russia remains committed to upholding the sanctions on paper, critics say that it is undermining attempts to isolate North Korea.

Russian diplomats in March effectively disbanded the UN panel responsible for monitoring North Korean sanctions.

South Korea on Friday summoned Russia's ambassador over the pact, with South Korean foreign minister Cho Tae-yul and US Secretary of State Antony Blinken condemning the deal as a threat to regional stability and security.

Putin, on a trip to Vietnam Friday, warned South Korea against arming Ukraine in response, saying that it would be a "big mistake."

Moscow "will... [make] decisions which are unlikely to please the current leadership of South Korea" if it goes ahead and sends weapons to Ukraine, Putin said, reported BBC News.

But he also said that South Korea has "nothing to worry about" from the new pact as long as it doesn't commit acts of aggression toward North Korea.

South Korea is among the US allies that provided Ukraine with aid in battling the Russian invasion, but so far, has stopped short of providing Kyiv with weapons.

Analysts from the US think tank Institute for the Study of War say Russia is attempting to remake Cold War-era alliances to counter US global power.