The websites of the Ukrainian armed forces and several Ukrainian ministries and banks have been crippled by a cyberattack, the Ukrainian government says.
The website of the Defense Ministry "probably suffered DDoS (distributed denial-of-service) attacks when an excessive number of requests per second was recorded," the ministry said on Twitter on February 15, adding that efforts to fix the problem and restore access were under way.
The ministry's Facebook and Twitter accounts were to be used as a backup for official communications until the sites return to normal operation. Two other websites, ArmyInform and Army FM, were also to be used, the Defense Ministry said on Facebook.
The Defense Ministry was one of at least 10 Ukrainian websites that stopped working due to DDoS attacks, AP reported. It said the Foreign Ministry and the Culture Ministry were among the others affected.
A communication and information security center within the Ministry of Culture and Information Policy did not say who it suspected was behind the attack, but a statement implied that it believed Russia was the culprit.
"It is not ruled out that the aggressor used tactics of little dirty tricks because its aggressive plans are not working out on a large scale," it said.
Relations between Western countries and Russia remain on edge due to more than 130,000 troops deployed near the border with Ukraine, prompting fears of war. It has denied that it plans an invasion as efforts to resolve the crisis diplomatically continue.
SEE ALSO: Biden Says Russian Attack On Ukraine Still Possible, Sees No Evidence Of Troop WithdrawalAt least two banks, Privatbank and Oschadbank, were also targeted by cyberattacks on February 15. Privatbank's outages were caused by a DDoS attack, the center said.
Users of Privatbank's Privat24 online application reported problems with payments and the application in general. Some users were not able to log in to Privat24, while others could not see their account balances and recent transactions.
The bank said the cyberattack affected only the Privat24 application and there was no threat to depositors' funds.
Oschadbank has also had failures and its Internet banking service was down.
The European Union said after cyberattacks that affected Ukrainian institutions in January that it would mobilize resources to help Ukraine deal with the cyberattack on its government websites.
European Union foreign-policy chief Josep Borrell said at the time that it was unknown who was behind the attack, but "we can guess."
White House cyber-official Anne Neuberger said earlier this month that Russia could use cyberattacks as part of its efforts to destabilize and further invade Ukraine.
Two U.S. technology companies -- Microsoft and Palo Alto Networks -- on February 4 said a hacking team that Ukraine says is controlled by Russian intelligence has targeted a wide range of organizations in the country.