WATCH: White House says they haven’t found the source of Ukraine cyber attacks

The White House says it has not yet determined responsibility for the cyber attacks Tuesday on Ukrainian government websites and banks, among other critical computer systems.

Psaki’s remarks in the player above.

A series of cyberattacks on Tuesday knocked the websites of the Ukrainian army, the defense ministry and major banks offline, Ukrainian authorities said, as tensions persisted over the threat of a possible Russian invasion.

Still, there was no indication the relatively low-level, distributed-denial-of-service attacks might be a smokescreen for more serious and damaging cyber mischief.

Speaking at the White House, press secretary Jen Psaki said, “We have been warning for weeks and months, both publicly and in our engagements with the Ukrainians as well as our European partners, about the potential for Russia to conduct cyber operations in Ukraine.”

READ MORE: Cyberattacks take down Ukrainian government and bank websites

But she added, at this point in time, the White House has nothing to report on attribution for the attacks.

At least 10 Ukrainian websites were unreachable due to the attacks, including the defense, foreign and culture ministries and Ukraine’s two largest state banks. In such attacks, websites are barraged with a flood of junk data packets, rendering them unreachable.

The attacks came as President Joe Biden warned anew that a Russian invasion of Ukraine remains “distinctly possible” despite claims from Moscow that some of its troops are pulling back from the Ukraine border.

Speaking in the White House East Room shortly before Psaki’s briefing, Biden said the U.S. has “not yet verified” Russia’s claim that some of its forces have started to withdraw.

Asked if Russia’s comments about a pull back of its troops are cause for “cautious optimism,” Psaki remained skeptical.

“We’ve seen this playbook before and especially given the history of President Putin and the Russians, their their history of false flag operations, of misinformation, we need to verify,” she said.