KIEV, Ukraine — The day started like most for Roman N. Klimenko, an accountant in Kiev who had just settled in at his desk, typing at a computer keyboard and drinking coffee. He was unaware that concealed within his tax preparation software lurked a ticking bomb.

That bomb soon exploded, destroying his financial data and quickly spreading through computer systems vital to Ukraine’s government — and beyond. The cyberattack, on Tuesday, was caused by a virus similar to one that wreaked global havoc less than two months ago.

Both had the appearance of hacker blackmail assaults known as ransomware attacks: screens of infected computers warn users their data will be destroyed unless ransoms are paid.

But in Ukraine’s case, a more sinister motive — paralysis of the country’s vital computer systems — may have been at work, cybersecurity experts said on Wednesday. And many Ukrainians cast their suspicions on Russia.