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.

A top Russian pro-war blogger has been killed in a bomb attack on a cafe in Russia, according to police.

The explosion on Sunday tore through a cafe in St. Petersburg, killing Vladlen Tatarsky, one of the best-known of the Russian military bloggers who have become influential during the war in Ukraine.

At least 30 other people were injured in the blast, according to the Ministry of Health. Video circulating online appeared to capture the aftermath, showing bloodied people emerging from the heavily damaged cafe.

The Russian Interior Ministry said an explosion has occurred in a cafe on the city's Universitetskaya Embankment.

"One person was killed in the incident, it was military correspondent Vladlen Tatarsky, the Russian Interior Ministry press center told reporters on Sunday.

Denis Pushilin, acting head of the Russian-backed Donetsk People’s Republic, issued a statement describing Tatarsky as "a great patriot" of the Donbass region of eastern Ukraine and Russia. Pushilin blamed the attack on the Kyiv regime, calling it a terrorist regime.

"A man with a difficult fate, Vladlen earned the respect of his comrades-in-arms because he lived and worked for the sake of truth and justice, for the sake of victory," Pushilin said of Tatarsky. "He managed to fight, and in the status of a military correspondent to make his contribution."

Pushilin said Tatarsky was to be awarded a medal "for the liberation of Mariupol" in eastern Ukraine.

It was the most serious bomb attack on a pro-war Russian figure inside Russia since the high-profile assassination of the Daria Dugina, the daughter of the ultra-nationalist Alexander Dugina, who was killed in a car bombing last year.

Tatarsky was a Russian ultra-nationalist and one of the best-known military bloggers, who strongly supported the war in Ukraine. He had also criticized the execution of the war by Russia’s military command.

Tatarsky had become a significant source of information for how the war was being fought on the Russian side.

His killing will likely set off speculation on whether Ukraine or Russia was behind his killing, similar to the Dugina episode.

In the Dugina case, U.S. intelligence sources eventually told The New York Times that Ukraine was behind the attack.

-News Patrick Reevell