Neither the White House nor North Korea's Ministry of Foreign Affairs immediately responded to CNET's request for comment.
"In furtherance of both, and after careful investigation, the USA today publicly attributes the massive "WannaCry" cyberattack to North Korea", he wrote.
This is seen by the administration as an option short of full-scale nuclear war, and the only such option available to them since they're bound and determined not to engage in direct diplomacy with North Korea.
The statement accused the USA of forcibly linking North Korea to the attack - that led to a huge outcry worldwide - to incite the global community against the North Korean regime, state-owned KCNA agency reported.
The North kept its firm stance against US President Donald Trump's administration, calling the allegation a serious political provocation to damage the country's image.
The WannaCry attack crippled hospitals, banks and companies around the world, and "highlights the capabilities that North Korea has in cyber", Kurtz said. WannaCry began spreading on May 12 this year and encrypted the files on around 300,000 computers in 150 countries. The North was also suspected of involvement in a cyberattack on Sony's United States subsidiary 3 years ago. Bossert described the company as "a strong partner", adding that there is "no fear that there's any wedge between us".
Bossert also said Microsoft had traced the attack to cyber affiliates of the North Korean government, and others in the security community have contributed their analysis.
Those conclusions didn't sit well with the North Koreans. The indiscriminate use of the WannaCry ransomware demonstrates North Korean actors using their cyber programme to circumvent sanctions.
The attack exploited a Windows vulnerability that was originally developed by the US National Security Agency, but was released in a stolen cache of NSA cyberweapons by a hacking group known as the Shadow Brokers.