Jens Stoltenberg, NATO Secretary General, who a few days earlier was in talks in Brussels with a Russian delegation calling for an end to cooperation with Ukraine, responded to the cyberattack by saying that NATO would strengthen its coordination with Kyiv on cyber defences.

“I strongly condemn cyberattacks against the Ukrainian government,” Stoltenberg said in a statement. declaration, adding: “NATO and Ukraine will intensify their cooperation on cybersecurity and we will continue our strong political and practical support.” A NATO spokesman said the alliance would sign an agreement in the coming days giving Ukraine access to a NATO information-sharing system to combat malware.

The European Union’s top diplomat, Josep Borrell, told a meeting of European foreign ministers on Friday that the bloc would mobilize cyber response teams and help Ukraine with cyber defenses.

Often, unraveling the digital threads of these cyber operations can take days or weeks, which is one of the attractions of their use in modern conflict. Sophisticated cyber tools have emerged in clashes between Israel and Iran, and the US has accused Russia of using hacking to influence the 2016 US election to benefit Donald J. Trump.

Ukraine has long been seen as a testing ground for Russian line operations, a sort of free-fire zone for cyberweapons in a country already embroiled in a real world war with Russian-backed separatists in two provinces from the east. The US government has attributed some of the most drastic cyberattacks of the past decade to Russian actions in Ukraine.

The tactics first seen in Ukraine then popped up elsewhere. A strain of Russian military spyware called X-Agent, or Sofacy, which Ukrainian cyber experts say was used to hack Ukraine’s Central Election Commission during a 2014 presidential election, for example, was later discovered. on the server of the Democratic National Committee in the United States. after the election hacking attacks in 2016.

Other types of malware like BlackEnergy, Industroyer and KillDisk, intended to sabotage computers used to control industrial processes, shut down electrical substations in Ukraine in 2015 and 2016, causing power outages, including in the capital, Kyiv.