US says North Korea 'directly responsible' for 'WannaCry' cyber attack

North Korea is "directly responsible" for the so-called WannaCry cyber attack that crippled hospitals, banks and other companies across the globe earlier this year, a senior White House official said on Monday.

"The attack was widespread and cost billions, and North Korea is directly responsible," Tom Bossert, the White House homeland security adviser, wrote in an opinion piece published online by the Wall Street Journal.

Bossert said anyone who harmed the United States would be held accountable, but he did not detail any specific actions Washington might take against Pyongyang, other than saying it would continue to pursue a "maximum pressure strategy."