KYIV, Ukraine — Ukraine fired six American-supplied longer-range missiles at Russia’s Bryansk region, Moscow said Tuesday, in what would be Kyiv’s first use of the weapons inside Russia in 1,000 days of war.

The reported use of the Army Tactical Missile System, known as ATACMS, came as Russian President Vladimir Putin formally lowered the threshold for using nuclear weapons, opening the door to a potential nuclear response by Moscow to even a conventional attack by any nation supported by a nuclear power. That could include Ukrainian attacks backed by the U.S.

A Telegram channel affiliated with the Ukrainian military posted a video Tuesday that it says shows U.S.-supplied ATACMS missiles being fired from an undisclosed location in Ukraine. The Associated Press could not independently verify the date and location the video was filmed.

Related Story: Moscow Warns the US Over Allowing Ukraine to Hit Russian Soil With Longer-Range ...

War Reaches Critical Turning Point

The developments marked a worrying new escalation in the conflict that has repeatedly ratcheted up international tensions. U.S. officials recently expressed dismay at Russia’s deployment of North Korean troops to help it fight Ukraine, while Moscow seethed when Washington eased restrictions on the ATACMS in recent days.

The 1,000-day mark has magnified scrutiny of how the war is unfolding and how it might end, amid signs that a turning point may be coming with U.S. President-elect Donald Trump entering the White House in about two months’ time. Trump has pledged to swiftly end the war and has criticized the amount the U.S. has spent on supporting Ukraine.

Neither Russia nor Ukraine can sustain the war for a long time, analysts say, though Russia is able to keep going for longer due to its vaster resources.

Ukraine’s forces are under severe Russian pressure on the battlefield at places on the about 1,000-kilometer (600-mile) front line where its army is stretched thin. Ukrainian civilians, meanwhile, have repeatedly been clobbered by Russian drones and missiles.

Related Story: As Trump Pushes Peace Talks, Ukraine Prioritizes Security Guarantees

Military Operations Intensify

On Tuesday, Ukraine claimed it hit a military weapons depot in Russia’s Bryansk region in the middle of the night, though it didn’t specify what weapons it used. The Ukrainian General Staff said that multiple explosions and detonations were heard in the targeted area, around Karachev.

Asked at a news conference if Ukraine had struck the Bryansk region ammunition depot with ATACMS, Ukraine’s President Volodymyr Zelenskyy declined to provide any details. However, he said, “Ukraine has long-range capabilities, including domestically produced long-range drones… and now we have ATACMS as well.”

In a statement carried by Russian news agencies, the Russian Defense Ministry said the military shot down five ATACMS missiles and damaged one more. The fragments fell on the territory of an unspecified military facility, the ministry said. The falling debris sparked a fire, but didn’t cause any damage or casualties, it said.

Neither side’s claims could be independently verified.

Karachev is roughly 115 kilometers (70 miles) from the Russia-Ukraine border. Ukraine in the course of the war has been able to reach much deeper into the vast country — but with drones rather than missiles. For instance, Russian officials have reported intercepting Ukrainian drones over Moscow, which is about 500 kilometers (310 miles) from the border and most recently Izhevsk, a city about 1,450 kilometers (900 miles) from the frontier.

Earlier on Tuesday, Ukrainian officials reported a third Russian strike in as many days on a residential area in Ukraine killed at least 12 people, including a child.

The strike by a Shahed drone in the northern Sumy region late Monday hit a dormitory of an educational facility in the town of Hlukhiv and wounded 11 others, including two children, authorities said, adding that more people could be trapped under the rubble.

On Sunday, a Russian ballistic missile with cluster munitions struck a residential area of Sumy in northern Ukraine, killing 11 people and wounding 84 others. On Monday, a Russian missile barrage sparked apartment fires in the southern port of Odesa, killing at least 10 people and wounding 43.

Zelenskyy said that the series of aerial strikes proved that Putin wasn’t interested in ending the war.

“Each new attack by Russia only confirms Putin’s true intentions. He wants the war to continue. Talks about peace are not interesting to him. We must force Russia to a just peace by force,” Zelenskyy said.

Zelenskyy told European Union lawmakers in a speech via video link that Russia has deployed about 11,000 North Korean troops along Ukraine’s borders and that the number could swell to 100,000.

He appeared in person at the Ukrainian parliament, where he presented what he called a “resilience plan” to dig in against the relentless Russian onslaught. He said he expects pivotal moments to occur in the war next year.

The plan outlines new approaches to army management, including the creation of a military ombudsman position and a new system of handling military contracts.

There are no plans to lower the mobilization age from the current 25, even though Ukraine is short-handed on the front line, especially in infantry.

Ukraine urgently needs to tackle its manpower difficulties on the front, but it can use the longer-range missiles in the meantime to slow the tempo of Russia’s recent advances, said Jack Watling, an analyst at the Royal United Services Institute, a London think tank.

“Ukraine’s partners can do little to change the character of the fighting on the line of contact, but by targeting capabilities that are currently giving Russia a battlefield advantage, time can be bought,” Watling wrote Tuesday.

Related Story: 8-Hour Russian Drone Barrage Keeps Kyiv on Edge as War in Ukraine Nears 1,000 ...

Next year, Zelenskyy said, Ukraine plans to produce at least 30,000 long-range drones and aims to manufacture 3,000 long-range missiles, reducing its dependence on Western military support.

A fuller version of the plan will be presented next month, he said.

NATO Secretary-General Mark Rutte said Western countries are debating further help for Ukraine — “more aid, more money we have to make available to them, particularly now that the North Koreans have come on board,” he said in Brussels.

Meanwhile, European Parliament President Roberta Metsola led a special plenary session on Ukraine marking “one thousand days of terror, suffering and unimaginable loss. One thousand days of courage, resilience and unbreakable spirits.”

“Your people are an inspiration to all who value freedom around the world,” she told Zelenskyy.