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.

Ukrainian Defense Minister Oleksiy Reznikov denied Ukraine was involved in the bombing of the Nord Stream pipeline, which carries natural gas from Russia to Germany. While the pipeline was not active at the time of the bombing last September, it was filled with fuel.

The denial comes after The New York Times reported that intelligence reviewed by U.S. officials suggests a pro-Ukrainian group carried out the Nord Stream bombings last year.

After the story broke, German Defense Minister Boris Pistorius warned against “jumping to conclusions” about who carried out the explosion, suggesting it could have been a “false flag” operation to blame Ukraine.

German authorities were reportedly able to identify the boat used for the sabotage operation, saying a group of five men and one woman using forged passports rented a yacht from a Poland-based company owned by Ukrainian citizens. The nationalities of the perpetrators are unclear, according to a separate report by Germany’s ARD broadcaster and Zeit newspaper.

“We have to make a clear distinction whether it was a Ukrainian group, whether it may have happened at Ukrainian orders, or a pro-Ukrainian group [acting] without knowledge of the government. But I am warning against jumping to conclusions,” Pistorius said on the sidelines of a summit in Stockholm.

A Russian diplomat said Russia has no faith in the U.S.‘s “impartiality” in the conclusions made from intelligence.

-ABC News’ Ellie Kaufman