Responding to Russia's accusation that the U.S. was behind Wednesday's drone attack on the Kremlin, White House spokesperson John Kirby said it was a "ludicrous claim."

"There's a word that comes to mind that I'm obviously not -- not appropriate to using on national TV," Kirby said on CNN on Thursday.

"I will just tell you Mr. Peskov is lying, and I mean, that's obviously, it's a ludicrous claim," he added. "The United States had nothing to do with this. We don't even know exactly what happened here, Kaitlin. But I can assure you, the United States had no role in it whatsoever."

Kirby said the U.S. does not have any information on who is behind the strike but are "trying to learn more about this as best we can."

-ABC News' Justin Gomez

Russian President Vladimir Putin's spokesman accused the United States of being involved in the drone attack on the Kremlin on Wednesday.

"We understand well that the decision about such terror attacks are taken not in Kyiv, but in Washington," Dmitry Peskov told reporters in a briefing. "Often targets are determined not in Kyiv but in Washington. They don't Kyiv the right everytime in choosing the means. In Washington they also clearly understand that we know that."

He added, "Without question. Such decisions -- the determining of targets and means -- are all dictated to Kyiv from Washington."

Peskov said it was important that Washington understand the "danger" of such involvement in an attack.

-ABC News' Patrick Reevell

Russian forces launched a "complex air strike" with "drones and missiles" on Kyiv early Thursday morning, the Kyiv City Military Administration said on Telegram.

The air raid siren went off in Kyiv for three and a half hours during the attack, the Kyiv City Military Administration said.

There were no casualties or injuries from the strikes.

"According to preliminary information, all the missiles and UAVs were destroyed," the Kyiv City Military Administration added.

This was the third attack on the capitol in four days, the administration said.

-ABC News' Natalia Kushniir

The U.S. Embassy in Ukraine sent an alert to Americans on Wednesday warning of an "ongoing heightened threat of missile attacks," including in Kyiv.

"In light of the recent uptick in strikes across Ukraine and inflammatory rhetoric from Moscow, the Department of State cautions U.S. citizens of an ongoing heightened threat of missile attacks, including in Kyiv and Kyiv Oblast," the alert stated.

The U.S. Embassy urged U.S. citizens to follow guidance from local authorities and to observe air alarms and shelter appropriately.

Russian airstrikes targeted several cities across Ukraine early Friday, killing at least 25 people, Ukrainian officials said.

The city of Uman in central Ukraine's Cherkasy Oblast was the worst affected. Several buildings were damaged or destroyed. One of the strikes hit an apartment building, killing at least 23 people, including four children, and injuring another 18 people, according to Cherkasy Oblast Gov. Ihor Taburets. The attack happened at around 4:30 a.m. local time, when most people would have been asleep. An entire section of the nine-story building collapsed, with 27 apartments completely destroyed. There were 109 people who lived in that part of the building, according to Ukrainian police. Rescue teams were expected to spend all day and night searching for survivors in the rubble.

It was the deadliest single attack on civilians in Ukraine since January.

Dnipro, Ukraine's fourth-largest city and a major industrial hub located in southeastern Dnipropetrovsk Oblast, was hit by "high-precision" strikes in the early morning hours, leaving a woman and a 3-year-old child dead, according to Dnipro Mayor Boris Filatov.

Russian strikes also targeted Kyiv, Ukraine's capital and largest city, but there were no reports of any casualties or damages. It was the first such attack on the capital in 51 days, according to the Kyiv City Military Administration. Preliminary data shows 11 cruise missiles and two drones were destroyed in Kyiv's airspace, the city military administration said.

-ABC News' Yulia Drozd, Will Gretsky, Natalia Kushnir and Joe Simonetti