The U.S. government has publicly attributed the massive “WannaCry” cyberattack early this year to North Korea.

The attack paralyzed the computer networks of hospitals, banks and businesses around the world. 

Thomas Bossert, Assistant to the U.S. President for Homeland Security and Counterterrorism, wrote a column for the Wall Street Journal on Monday titled, "It’s Official: North Korea Is Behind WannaCry."

He said the cyberattack cost billions of dollars and put lives at risk. Bossert added that the U.S. will apply maximum pressure on the North to suppress its growing cyber capabilities.

The WannaCry ransomware targeted computers running Microsoft Windows and users with infected files were asked to pay a ransom.

The worldwide attack which began in May affected more than 230-thousand computers in some 150 nations. The UK's National Health Service system was also badly affected. 

North Korea has been cited as the culprit several times but it's the first time the U.S. government has officially recognized it. 

Bossert said the attack being connected with the North Korean government was determined through careful investigation. Washington is expected to formally announce the findings on Tuesday. 

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