ISTANBUL 

North Korea vowed to defend its sovereignty on Sunday in response to joint military exercises by South Korea, the US and Japan, according to Seoul-based Yonhap News.

A statement coincided with the increasingly close alignment between North Korea and Russia, marked by a recent treaty between Russian President Vladimir Putin and North Korean leader Kim Jong-un to establish a "comprehensive strategic partnership," it said.

Pyongyang's Foreign Ministry, quoted by the official Korean Central News Agency, said: "We will protect our national sovereignty, security interests, and regional peace through decisive and powerful actions."

It did not specify what the actions would entail.

The joint military exercises, dubbed "Freedom Edge," concluded Saturday after three days.

It marked the first time South Korea, the US and Japan held a trilateral exercise across multiple domains including air, maritime, underwater and cyber to bolster their collective deterrence against North Korean threats.