For the first time, President Biden has given Ukraine the green light to use powerful American long-range weapons for strikes inside Russia, a U.S. official told NPR on Sunday.

The missiles, known as the Army Tactical Missile System, or ATACMS, can travel about 190 miles. Their use would enable Ukrainian troops to strike Russia's weapons stockpiles, logistical centers and airfields — which could help stop Russian forces from advancing on the battlefield and attacking Ukrainian cities.

The U.S. official, who wasn't authorized to speak publicly about the decision, said the U.S. is allowing Ukraine to use the weapons to target in and around Kursk — the same region where some 10,000 North Korean troops were recently deployed, according to the U.S. and its allies.

The authorization marks a significant reversal in U.S. policy. Until recently, the Biden administration resisted allowing Ukraine to fire American long-range missiles into Russian territory for fear that it would only escalate the war.

The U.S. confirmed in the spring that it had sent ATACMS to Ukraine, with the caveat that the weapons would only be used inside Ukrainian territory.

British officials will likely follow suit in allowing Ukraine to use their Storm Shadow long-range missiles in Russia, the U.S. official said. These missiles can travel about 155 miles. The British needed U.S. approval because these missiles contain U.S. components.

It's unclear how many long-range ATACMS Ukraine has, but the numbers are limited, since Ukraine already used some of the weapons on targets inside its territory.

A separate source on Capitol Hill, who also wasn't authorized to speak publicly, said the decision is unlikely to be a game-changer in the war because of the limited number of such missiles and because Ukraine is already using drones to hit Russian targets.

Ukrainian President Volodymyr Zelenskyy had been pushing for the U.S. policy change for at least several months.

In his nightly video address on Sunday, Zelenskyy said Ukraine's long-range strike capabilities will be key to its victory. "Today, there's a lot of talk in the media about us receiving permission for respective actions," he said. "But strikes are not carried out with words. Such things are not announced. Missiles will speak for themselves."

Russia launched 210 missiles and drones at Ukraine on Sunday, Zelenskyy said, attacking the energy system and other critical infrastructure in what he described as one of Russia's largest attacks in the war so far.

Zelenskyy said Russian President Vladimir Putin responds to strength, not diplomacy. "We need to be strong. We need to invest time not in talking to someone in Moscow, but in really forcing Russia to end the war," he added.

The war has escalated since Ukrainian forces carried out a surprise incursion into Russia's Kursk region in August. The attack was viewed as a breakthrough for Ukraine and a setback for Russia. Then, in October, North Korea sent thousands of its troops to Kursk to help Russia fight off the Ukrainian incursion.

The policy shift comes just over two months before President-elect Donald Trump will return to the White House. Trump has criticized the amount of aid given to Ukraine in its fight against Russia and claimed he could end the war in 24 hours, though he has not explained how.

Ukrainian soldier and historian Maksym Sviezhentsev, speaking near the frontline in Ukraine, said he wished the restrictions on ATACMS never existed in the first place and hopes the Trump administration will not revoke the authorization.

"I don't want to sound ungrateful. The help of the U.S. has still been invaluable. But it has not been enough to let us win the war," he said. "I'm just thinking how many lives could be saved if those restrictions were lifted a year ago?"

NPR's Tom Bowman contributed reporting.