(NewsNation Now) — Ukraine’s Parliament, banks and government offices are being “bombarded by waves” of cyber attacks as Russia invades the Eastern European nation — hitting Kyiv, other cities and military bases with airstrikes and shelling early Thursday morning.

Most of the online assaults were denial-of-service attacks — where sites are flooded with so many users they crash, says Lester Munson, a senior fellow at the National Security Institute. 

The websites of Ukraine’s defense, foreign and interior ministries were hit. Many of the same sites were similarly knocked offline Feb. 13-14 in attacks that the U.S. and U.K. governments quickly blamed on Russia’s GRU military intelligence agency.

Other cyberwarfare tactics included using wiper malware, which wipes the hardware of a computer, to cripple hundreds of computers and Ukrainian networks. 

“Russia has a very sophisticated cyber attack capability,” Munson said. “Just in the United States in the last couple of years, we’ve had Russian hackers attack our government agencies, attack fuel pipelines and even attack meat producers.”

Twitter responded to the attack with advice for users in conflict zones on how to protect their accounts, including strengthening account security with two-factor authentication and disabling tweet location data. 

Experts say it is possible this online attack was planned for as far back as December 2021 — but was timed to coincide with an invasion. Under both the Trump and Biden administrations, the U.S. has worked with Ukraine to boost the country’s cyber security. 

“I think we’re about to find out very quickly how effective that assistance is going to be,” Munson said. 

Meanwhile, civilians are piling into cars and trains en masse throughout Ukraine, with some fleeing to nearby countries of Poland and Germany. At least 40 people in Ukraine have died and dozens are wounded. The Russian military is also reporting casualties.

“This is terrible. We need the world to stop it. Immediately,” said Victor Zhora, senior Ukrainian cyber defense official.

President Joe Biden met with his National Security Council and G7 allies Thursday morning. He is expected to announce new sanctions to punish Russia for the “unprovoked and unjustified attack” on Ukraine. Watch live at 12:30 p.m. EST here.

Cyberattacks have been a key tool of Russian aggression in Ukraine since before 2014, when the Kremlin annexed Crimea and hackers tried to thwart elections. They were also used against Estonia in 2007 and Georgia in 2008. The West blames Russia for some of the most damaging cyberattacks on record, which caused more than $10 billion of damage globally.

The intent can be to sow panic, confuse and distract. 

“There’s a whole host of activities that Russia has already engaged in,” Munson said, “and there are other things they could engage in in the future.”

As the conflict in Ukraine continues, NewsNation will bring Americans the latest developments from abroad and insights into its impact at home throughout our newscasts. We’re dropping the paywall on our live stream so it’s available to everyone. You can watch NewsNation’s programming, including the latest on Ukraine, at the top of the hour from 7-10 a.m. and 5-11 p.m. ET.

The Associated Press contributed to this story.