North Korea says US ransomware accusation a 'grave political provocation', vows to retaliate

North Korea has described a US accusation that it was behind a ransomware attack as a "grave political provocation" and vowed to retaliate.

Homeland security adviser Tom Bossert wrote in a Wall Street Journal op-ed published Monday that North Korea will be held accountable for May's WannaCry ransomware attack that infected hundreds of thousands of computers worldwide.

The North's Foreign Ministry repeated Thursday it had nothing to do with the attack. It said it will never tolerate such "reckless" US claims but didn't say how it would respond.

It's not unusual for Pyongyang to issue harsh rhetoric against Washington and Seoul. Thursday's warning came amid heightened animosities following the North's test-launch of its most powerful missile last month.