An old method of Hacking, distributed denial of service, or DDoS, is being used by Ukrainian hackers as a tool to fight against Russia's military operation in Ukraine.

The hackers are part of an informal group of volunteers in Ukraine's IT army. 

Russian websites are flooded with fake traffic in the old and simple method. The hackers are encouraging others to engage in the attacks as a way of "participating".

A few hacktivists have also vandalized Russian websites, generally with pro-Ukraine or anti-Vladimir Putin statements, however, such attempts are frequently rapidly restored and there is no evidence that they are widely viewed.

Last week, the Russian Foreign Ministry Spokesperson said the website of the Russian Foreign Ministry is under DDoS attacks around the clock, 

"The [ministry's] website, like the websites of other government agencies, has been under DDoS attacks around the clock for these couple of weeks," Zakharova told the Solovyov Live show on YouTube.

US President Joe Biden on Monday warned US companies of intelligence that suggests a Russian "cyber threat", urging US businesses to "immediately" prepare defenses.

"If you have not already done so, I urge our private sector partners to harden your cyber defenses immediately," he said in a statement.

Earlier, the National Computer Network Emergency Response Technical Team/Coordination Center of China has reported several cyberattacks since late February.

The breaches all came from abroad the Republic and coincide with the Russian military operation in Ukraine.

Xinhua reported that most of the attacks came from the US to control Chinese computers and utilize them against Russia, Belarus, and Ukraine.

87% of the attacks were to be used against Russia.