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.

The leader of of Russia's Wagner mercenary group appeared on Sunday to ditch plans to withdraw his forces from Bakhmut in eastern Ukraine after receiving promises overnight that they would get all the arms needed to capture the devastated city.

Yevgeny Prigozhin said in a new audio message that the Kremlin has promised to resupply his Wagner Private Military Company with as much ammunition and weapons as they need.

Prigozhin said that for the first time he received a response to the situation regarding the shortage of ammunition. He said on Saturday night that the relevant companies promised to deliver everything necessary to continue the offensive in Bakhmut.

"Overnight we received a combat order, for the first time in all this time," Prigozhin said. "We have been promised as much ammunition and weapons as we need to continue further operations. We have been promised that everything needed to prevent the enemy from cutting us off (from supplies) will be deployed on the flank," he added.

In addition, Russian Army Gen. Sergei Surovikin will personally deal with issues of interaction between the Wagner PMC and the Ministry of Defense, Prigozhin said. "This is the only man with the star of an army general who knows how to fight," Prigozhin said of the Russian Defense Ministry assigning Surovikin to work alongside Wagner.

Surovikin commanded Russia's Ukraine campaign for several months before the chief of the General Staff, Army Gen. Valery Gerasimov, was given overall operational command above him.