"Wannacry's attack is widespread and causes losses of up to billions of dollars and North Korea is directly responsible for the attack," said Thomas P. Bossert, Trump's home security adviser in an article in the Wall Street Journal.
"We're not saying this without thinking, it's based on the evidence, and we're not the only ones who found that evidence."
On Tuesday at the White House, Bossert mentioned that the WannaCry attack was a defining moment, saying that the attack affected individuals, companies and governments around the world.
The attacks also create financial losses and endanger the lives of people. "This is a disrespectful attack aimed at creating chaos and destruction," Bossert told a news conference.
"North Korea has shown that they want to threaten the whole world, either through a nuclear program or a cyber attack."
Bossert admits that the United States has no choice but to retaliate to North Korea and suppress the isolated state to change its stance in any way except to attack it directly.
North Korea is one country with few partners. However, he feels, announcing that North Korea is responsible for WannaCry's attacks in public is still an important step.
"We will keep them accountable and we will announce this and we will embarrass them," Bossert said. North Korea allegedly created a virus paired with ransomware to encrypt data on victim computers and demanded victims to pay if they wanted their data back.