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.

Speaking to ABC News' George Stephanopoulos on "Good Morning America," U.S. Secretary of State Antony Blinken discussed where things stand in the Russia-Ukraine war on Friday, one year after it began.

"Ukraine is still standing, it remains free, it remains independent," Blinken said. "Putin's first objective was to erase Ukraine from the map, to erase its identity, to absorb it into Russia. That has failed and will never succeed."

"Now, there's a fierce battle going on for the territory that Russia has seized," he added. "Ukraine's gotten about 50% of what Russia's taken since last February and now, there's a fight for the rest."

When asked how long Ukraine can hold on, with its economy devastated and Russian President Vladimir Putin seemingly preparing for a long war, Blinken said he thinks "the Ukrainians are the ones who are going to fight to the finish."

"There's one big difference: The Ukrainians are fighting for their country, for their land, for their future; the Russians are not," he noted. "And at the end of the day, assuming the support continues from so many countries around the world -- material support, military, economic, humanitarian -- Ukraine will succeed."

Blinken said it's "hard to predict" when the war will end.

"No one wants peace more than the Ukrainians, but it has to be a just and durable peace," he added. "Just in terms of reflecting the basic principles that are at the heart of the U.N. Charter, which is territorial integrity of countries, their sovereignty. And durable in the sense that wherever it lands, we don't want it to land in place where Russia can simply repeat the exercise a year or two or five years later."