Ukraine used a newly delivered Patriot air-defense system to intercept the most sophisticated missile in Russia’s arsenal for the first time over Kyiv this week, the Ukrainian Air Force said on Saturday.

It was the first time Ukraine said that its military had used the advanced American-made missile system, long coveted by the Ukrainians.Lt. Gen. Mykola Oleshchuk, the commander of the Ukrainian Air Force, said that the Patriot system was used to shoot down a hypersonic Kinzhal missile fired by Russia over the capital on Thursday.

“I congratulate the Ukrainian people on a historic event,” General Oleshchuk said in a statement posted on the Telegram messaging app. “Yes, we have shot down the ‘unparalleled’ ‘Kinzhal.’”

There was no immediate confirmation from Ukraine’s Western allies, including the United States, of the use of the Patriot or whether it had hit a hypersonic missile. The U.S. military’s European Command did not immediately respond to a request for comment.

The Patriot is by far the most expensive single weapon system that the United States, Ukraine’s main military benefactor, has supplied to Ukraine, at a total cost of about $1.1 billion: $400 million for the system and $690 million for the missiles.

Ukraine had been pleading with the Pentagon to provide it with Patriot systems since the start of the war and the White House approved the request in December. Last month, Ukraine confirmed that the first Patriot systems had arrived. For more than a year, Ukraine had no air-defense system that could counter Russia’s arsenal of ballistic or hypersonic missiles like the Kinzhal.

The powerful explosion that officials said was air defense firing in the skies above central Kyiv rattled windows and jolted people out of bed. Fragments from the explosion littered the streets not far from the government quarter in the heart of the city and were collected by teams of forensic experts.

General Oleshchuk said the military waited to report that the Patriot had been used to protect operational security. He urged the public not to share information about air defenses as they work to counter Russian missiles and drones.

“We will definitely report what, where, with what, and when it was shot down,” he said. “All in its own time.”

While Kyiv and other cities across Ukraine have been bombarded with missiles, rockets, drones and bombs for more than a year and thousands of civilians have been killed in Russian onslaughts, the repeated attacks on Kyiv by Russian drones over the past two weeks have put many in the city on edge.

Ukraine has become adept at shooting down Russian cruise-missiles and drones — often knocking some 70 to 80 percent of them out of the sky in any particular attack — but the ones that make it through the complex air defense network can do tremendous damage.

The Kinzhal, or Dagger, is a modified version of the Russian Army’s Iskander short-range ballistic missile, which is designed to be fired from truck-mounted launchers on the ground. Launching the missile from a warplane at high altitude, instead of from the ground, leaves it with more fuel to use to reach higher speeds.

Ukraine’s Air Force has said that Russia has used around 50 Kinzhals over the course of the war, including during the sustained assault on the Ukrainian energy grid in the fall and winter.

Depending on where Russia fires a Khinzal from, it can reach the Ukrainian capital in a matter of minutes.

The Patriot system works most effectively as part of what the U.S. military calls a “layered defense” that includes other air defenses used to down or thwart drones and warplanes, as well as a range of cruise and ballistic missiles, U.S. officials say. Its general ability to counter weapons like Russia’s Kinzhal hypersonic missile is as yet unknown.

Following the U.S. pledge to provide the Patriot systems, Ukrainian soldiers were dispatched to Fort Sill, Oklahoma, for a 10-week crash course in how to use them. They completed the training at the end of March and those soldiers are now training others in Ukraine.

One single interceptor missile costs about $4 million, according to the Center for Strategic and International Studies. Each launcher costs around $10 million.

After explosions over the Kremlin last week, Russian officials accused Ukraine of staging a drone attack with U.S. guidance and called for aggressive retaliation. Ukrainian officials have said the episode was likely staged by the Russians.

Here’s what else is happening in Ukraine:

Blast wounds a prominent Russian: A car bombing has injured a prominent Russian nationalist writer and killed his driver, Russian state media reported on Saturday, citing unnamed emergency services. The state-run Tass news agency said that the writer, Zakhar Prilepin, was wounded but conscious. Preliminary information showed that an explosive device had been planted under Mr. Prilepin’s car in Nizhny Novgorod, Tass reported, but did not say who was believed to be behind the attack.

Russification efforts: Ukraine’s military said on Saturday that Russian officials are intensifying pressure on Ukrainian civilians in illegally annexed areas to obtain Russian passports, with occupation authorities in the town of Starobilsk going from home to home to enforce a new edict that allows for those who do not cooperate to be removed from their homes.

The claim could not be independently verified. Russia has not allowed international journalists or organizations to access areas under its control.

Ukrainian officials said investigators have been gathering evidence in recent days about efforts to force people to pledge allegiance to the Russian Federation by getting a passport or be considered foreigners without legal residency. President Vladimir Putin of Russia signed a decree on April 27 that says those who refuse can be deemed a threat and “deported,” according to the policy.