WASHINGTON—The White House blamed Russia on Friday for this week’s cyberattacks targeting Ukraine’s defense ministry and major banks and warned of the potential for more significant disruptions in the days ahead. Anne Neuberger, the Biden administration’s deputy national security adviser for cyber and emerging technologies, said the United States had rapidly linked Tuesday’s attacks to Russian military intelligence officers. Britain joined the United States in blaming the GRU military intelligence agency for the distributed denial-of-service attacks that unfolded as tensions escalate between Russia and Ukraine. The attacks, which knocked government websites and a couple of major banks offline for much of the day, were of “limited impact” since Ukrainian officials were able to quickly get their systems back up and running, Neuberger said. But she said the Russians could also be laying the groundwork for more disruptive activities that could accompany an invasion of Ukraine. “We do expect that should …