North Korean leader Kim Jong Un
North Korean leader Kim Jong UnReuters

North Korean leader Kim Jong Un on Thursday night ordered the country to improve nuclear attack capability by continuing to conduct more tests, Reuters reports, citing the official KCNA news agency.

Kim's remarks came as he watched a ballistic missile test. The report did not say when the test took place but it was likely referring to the launch of two short-range missiles by North Korea on Thursday that flew 500 km (300 miles) and splashed into the sea.

"Dear comrade Kim Jong Un said work ... must be strengthened to improve nuclear attack capability and issued combat tasks to continue nuclear explosion tests to assess the power of newly developed nuclear warheads and tests to improve nuclear attack capability," KCNA said.

The North Korean leader has upped his rhetoric in recent days, saying earlier this week his country now possesses nuclear warheadssmall enough to fit on ballistic missiles.

Last week, Kim ordered his country to be prepared to use nuclear weapons “at any time”.

And on Sunday, North Korea threatened "indiscriminate" nuclear strikesagainst South Korea and the United States if the two allies push ahead with joint military drills.

Tension rose sharply on the Korean peninsula after the North conducted its fourth nuclear test in January and fired a long-range rocket last month leading to the UN Security Council to adopt a new sanctions resolution.

Conducting more nuclear tests would be in clear violation of UN sanctions which also ban ballistic missile tests, although Pyongyang has rejected them, noted Reuters.

North Korea has a large stockpile of short-range missiles and is developing long-range and intercontinental missiles.