Ukraine Sunday blamed Russia for the defacement of government websites, contending it was part of Moscow's "hybrid war" against the former Soviet republic.
With Russia already massing 100,000 military troops along Ukraine's eastern flank, Ukrainian officials said, 'All evidence indicates that Russia is behind the cyberattack."
"Moscow continues to wage a hybrid war and is actively building up its forces in the information and cyberspaces,' the ministry statement said, after Microsoft said dozens of computer systems at various Ukrainian government agencies had been infected with destructive malware disguised as ransomware.
Russia has repeatedly denied Ukrainian accusations of hacking.
The cyberattack comes amid the threat of a Russian invasion, eight years after Moscow annexed Ukraine's Crimean Peninsula.
Diplomatic talks to resolve the tense standoff appear to be at a stalemate after several meetings in Geneva, Brussels and Vienna last week did not result in any resolution.
White House National Security Adviser Jake Sullivan told CBS News's "Face the Nation" show that the United States remains ready for further diplomatic talks with Russia over its troop deployment but will respond with significant economic sanctions against Moscow if President Vladimir Putin invades Ukraine.
Microsoft said Saturday that it first detected the malware on Thursday, coinciding with the attack that simultaneously took about 70 Ukrainian government websites offline temporarily.
Some material in this report came from The Associated Press and Reuters.