Moscow says Ukrainian forces have taken advantage of President Biden's green light and launched 6 U.S.-made ATACMS (Army Tactical Missile Systems) into Russian territory Tuesday.

Russia says it shot down five of the missiles and damaged the sixth. It added that debris landed in the area of a Russian military facility, but that no casualties or damage beyond a small fire.

Ukraine did not immediately confirm the use of ATACMS on Tuesday, but officials did announce an attack on a military facility in Russia's Bryansk region, the same region where Moscow says the missiles fell.

The attack came just two days after President Biden approved Ukraine to use American long-range missiles on Russian soil, an escalation that Russian President Putin previously indicated would be an act of war.

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According to a senior U.S. official, Biden's decision was spurred by the Russian decision to invite 10,000 North Korean soldiers into the fight against Ukraine in Kursk. A second official told Fox that it is unclear if Biden plans to approve the use of the missiles outside the Kursk region.

The announcement came after Great Britain and France authorized Ukraine to launch SCALP/Storm Shadow missile strikes, according to French outlet Le Figaro.

Putin has previously said that giving Ukraine the green light on missile use would effectively mean that the U.S. and NATO are "in the war."

"Flight assignments for these missile systems can, in fact, only be entered by military personnel from NATO countries. Ukrainian servicemen cannot do this. And therefore, it is not a question of allowing the Ukrainian regime to strike Russia with these weapons or not. It is a question of making a decision whether NATO countries directly participate in the military conflict or not," Putin said in September.

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"If this decision is made, it will mean nothing less than the direct participation of NATO countries, the United States, and European countries, in the war in Ukraine," he added.

Meanwhile, President-elect Trump's transition team is expected to soon announce a peace envoy to assist in negotiations between Ukraine and Russia. Trump argued on the campaign trail that he could solve the conflict before entering office.

This is a developing story. Check back soon for updates.