“In June 2017, the Russian military launched the most destructive and costly cyber-attack in history,” said the White House press secretary in a statement released on Wednesday.

The so-called NotPetya attack of June 2017 “was part of the Kremlin’s ongoing effort to destabilize Ukraine and demonstrates ever more clearly Russia’s involvement in the ongoing conflict. This was also a reckless and indiscriminate cyber-attack that will be met with international consequences.”

The statement did not detail what the consequences would be, but “a senior White House official” told Reuters the US government is “reviewing a range of options.”

The White House’s remarks echoed a statement released earlier the same day by the United Kingdom’s foreign that the Russian military was behind the attack. “The decision to publicly attribute this incident underlines the fact that the UK and its allies will not tolerate malicious cyber activity,” said the ministry’s statement. “The attack masqueraded as a criminal enterprise but its purpose was principally to disrupt.”

The Russian government denied the accusation, calling it “Russophobic.”

The NotPetya malware attack started in Ukraine and spread globally, hitting transportation providers Maersk and TNT, among other companies. The IT system of Maersk, the world’s largest ocean csrrier, were reported down on June 27 thanks to the massive attack. Russia’s biggest oil company, Ukrainian banks, advertising firms, and pharmaceutical companies were among other concerns hit by the ransomware attack, which involved the spread of an information technology virus through a Ukrainian tax software product. The malware was spread by downloading Word documents or PDF files attached to emails.

On June 28, FedEx announced that the worldwide operations of its TNT unit were affected by the cyber attack. TNT operates in Ukraine and uses the software that was compromised, which allowed the virus to infiltrate systems and encrypt data.

In early July, an investigation by the NATO Cooperative Cyber Defense Center of Excellence concluded that a state actor was behind the attack with the most likely culprit being Russia.

Experts said that the attack could have been defended with the installation of a simple security patch, a step urged on its software users by Microsoft after an earlier attack.