Russia-Ukraine updates: Putin suspends key US-Russia nuclear treaty in speech denouncing West

Russian attacks have hit 30% to 40% of Ukraine's overall national power infrastructure, Ukraine's Energy Minister Herman Halushchenko told Reuters in an interview.

"We see that they targeted a number of new [facilities], but also they shelled [facilities] which had been already shelled before to destroy them absolutely," Halushchenko said.

Asked about the scale of the damage, Halushchenko said Russian attacks have hit at least half of Ukraine's thermal generation capacity and caused billions of dollars worth of damage.

Halushchenko said electricity imports could be one of the options Ukraine pursues to get through the crisis.

-ABC News' Jason Volack

U.S. Defense Secretary Lloyd Austin spoke with his Russian counterpart, Minister of Defense Sergey Shoygu, for the second time since the invasion of Ukraine on Friday.

"Secretary Austin emphasized the importance of maintaining lines of communication amid the ongoing war against Ukraine," the Pentagon said in a brief statement.

The first call between the two was in May and lasted an hour. Officials did not say how long the Friday call was.

-ABC News' Luis Martinez

The U.S. believes Iranians are "on the ground" in Ukraine to assist Russia with its drone operations, White House spokesman John Kirby told reporters Thursday.

"We can confirm that Russian military personnel that are based in Crimea have been piloting Iranian [drones] and using them to conduct strikes across Ukraine, including strikes against Kiev in just recent days. We assess that Iranian military personnel were on the ground in Crimea and assisted Russia in these operations," Kirby told reporters.

Kirby did not know how many Iranians are in Crimea, but said the U.S. knows it is "a relatively small number."

Kirby specified that the Iranians "have put trainers and tech support in Crimea, but it's the Russians who are doing the piloting."

“We're going to continue to vigorously enforce all U.S. sanctions on both the Russian and Iranian arms trade. We're going to make it harder for Iran to sell these weapons to Russia. We're going to help the Ukrainians have what they need to defend themselves against these threats."

-ABC News' Justin Gomez

The Justice Department will "continue" to be "relentless" in its pursuit to hold those responsible for war crimes and other atrocities in Ukraine accountable, U.S. Attorney General Merrick Garland said Thursday, while sitting next to his German counterpart, Minister of Justice Christine Lambrecht.

"We are committed to finding ways to expand our cooperation with our German partners in these efforts," Garland said.

Garland also thanked Germany for its help in apprehending a suspect accused of getting sensitive technologies to Russia as part of an indictment announced Wednesday.

The Justice Department charged five individuals including Yury Orekhov, the alleged mastermind behind the plot. Orekhov was arrested in Germany as part of the Justice Department's task force KleptoCapture, which is cracking down on Russian-related crimes as the war in Ukraine continues.

Asked if any U.S. intelligence was compromised after Germany replaced its head of cybersecurity over alleged ties to Russia, Garland didn't answer, saying intelligence sharing is what makes the relationship with Germany so strong.

-ABC News' Luke Barr