The United States administration claimed North Korea was “directly responsible” for the WannaCry ransomware attack that affected hospitals, businesses, and banks across the globe earlier this year.

The malware attack claimed to have affected at least 300,000 computers across 150 nations, causing damage of billions of dollars.

According to a BBC report, Homeland Security Advisor and an aide of President Donald Trump, Thomas Bossert, made the accusations while speaking with the Wall Street Journal. He made the claims asserting they were “based on evidence” and the North should be held “accountable” for the attack.

“The attack was widespread and cost billions, and North Korea is directly responsible,” he wrote in an op-ed in the Wall Street Journal. “We do not make this allegation lightly. It is based on evidence.”

“North Korea has acted especially badly, largely unchecked, for more than a decade, and its malicious behavior is growing more egregious. WannaCry was indiscriminately reckless,” Bossert further wrote.

"As we make the internet safer, we will continue to hold accountable those who harm or threaten us, whether they act alone or on behalf of criminal organizations or hostile nations. The toolkits of totalitarian regimes are too threatening to ignore. When we must, the U.S. will act alone to impose costs and consequences for cyber malfeasance,” he added.

A senior White House official, under the condition of anonymity, said the U.S. will make an official statement Tuesday confirming its stand on North Korea being behind the cyber attack, Reuters reported.

With a "very high level of confidence," the U.S. government affirmed a hacker group that goes by the name “Lazarus Group,” which works for North Korea, carried out the attack.

The U.S. is not the first one to accuse North Korea of being the mastermind of the attack. Earlier in November, U.K. government said it was "all but certain" North Korea carried out the attack.

Meanwhile, Microsoft president Brad Smith, in an interview with ITV News at Microsoft's headquarters in Redmond, said Pyongyang was behind the ransomware attack.

“I think at this point that all observers in the know have concluded that WannaCry was caused by North Korea using cyber tools or weapons that were stolen from the National Security Agency in the United States,” he said.

“I think over last six months we've seen threats come to life, unfortunately, in the new and more serious way. The problem has become bigger. We need governments to come together as they did in Geneva in 1949 and adopt a new digital Geneva Convention that makes clear that these cyber-attacks against civilians, especially in times of peace, are off-limits and a violation of international law,” he added.

The WannaCry cyberattack — the largest ransomware attack in history that took place in May — infected computers including hospitals, universities, and government agencies across the world. The hackers also demanded a $300 bitcoin ransom from each of their victims within a span of 72 hours or threatened to raise the ransom price and lock the data permanently.