MOSCOW — Ukraine fired a series of ATACMS missiles inside Russia, marking the first attack using the U.S.-made longer-range weapons in 1,000 days of war.

The U.S. official, who was not authorized to speak publicly on the matter, told NPR that Ukraine fired seven U.S.-made Army Tactical Missile System into Russia, striking a weapons depot near the town of Karachev, in Russia’s Bryansk region, about 70 miles from Ukraine.

It is reported Russian air defense systems S-400 intercepted five missiles and shot down one.

Earlier Tuesday, Russia’s Defense Ministry said Ukrainian forces fired six ATACMS into Russia, and that Russian air defense systems destroyed five of the missiles mid-flight and damaged a sixth, whose fragments started a small fire on the ground.

No injuries were reported.

Russia has said that Ukraine’s use of long-range ATACMS missiles against its territory marked a “new phase of the Western war” against Moscow, and has said it will react “accordingly”.

“This is, of course, a signal that they want to escalate,” Russian Foreign Minister Sergey Lavrov, speaking at a Group of 20 (G20) news conference in Brazil, said of the attack.

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.

NPR/ Al Jazeera