Ukraine’s state-owned telecommunications company, Ukrtelecom, which is used by the country’s military, experienced a massive cyberattack on Monday.
“Today, the enemy launched a powerful cyberattack against Ukrtelecom’s IT-infrastructure,” Yurii Shchyhol, chairman of the State Service of Special Communication and Information Protection of Ukraine, said, according to Reuters.
“The attack was repelled. And now Ukrtelecom has an ability to begin restoring its services to the clients,” Shchyhol added.
Company spokesperson Mikhail Shuranov added that the attack was “repulsed” and services had “gradually resumed,” Reuters reported.
Services were back up roughly 15 hours after the “ongoing and intensifying nation-scale disruption to service,” according to NetBlocks, a company that monitors internet outages.
NetBlocks called it the “most severe” cyberattack since the Russian invasion of Ukraine began on Feb. 24, knocking services down to just 13 percent of pre-war levels.
Triolan, a smaller Ukrainian telecom company, endured a similar attack earlier this month, causing some local customers to lose access.
The White House has warned Russia is also considering “options for potential cyberattacks” targeting U.S. critical infrastructure.
“To be clear, there is no certainty there will be a cyber incident on critical infrastructure,” White House deputy national security adviser for cyber and emerging technology Anne Neuberger said last week.
“So why am I here? Because this is a call to action and a call to responsibility for all of us,” she added, urging private companies to up their cybersecurity measures.
But Russia has dismissed those accusations, with Kremlin spokesperson Dmitry Peskov saying “the Russian Federation, unlike many Western countries, including the United States, does not engage in state-level banditry.”