This article is by Sarah Kim and read by an artificial voice. Ukraine fired six U.S.-supplied long-range missiles at Russia's southwestern Bryansk region, Moscow's Defense Ministry said Tuesday. This marks the first reported use of the American-made Army Tactical Missile System, known as ATACMS, within Russia, and comes as Russian President Vladimir Putin earlier Tuesday formally lowered Moscow's threshold for the use of nuclear weapons. Russia's Defense Ministry said in a statement that Ukraine's military used six ATACMS to strike a facility in the Bryansk region at 3:25 a.m. Moscow claimed that five of the missiles were shot down and another was damaged. It said that fragments led to a fire at a military facility, but there were no casualties or damages. Senior U.S. and Ukrainian officials confirmed that the Ukrainian military used the missiles to strike into Russia for the first time, reported the New York Times Tuesday. The report said that the predawn attack struck an ammunition depot in Bryansk, citing Ukrainian officials. U.S. President Joe Biden on Sunday authorized the first such use of ATACMS by Kyiv, likely in response to North Korean troops joining Russia's war on Ukraine. In response, Putin on Tuesday approved of lowering the bar for a nuclear strike in response to a broader range of conventional attacks. Russia's updated nuclear doctrine reflects that an attack from a nonnuclear state, if backed by a nuclear power, will be treated as a joint attack on Russia. He added that the use of nuclear weapons would be a "last resort measure." The U.S. government informed the South Korean government in advance of its decision to allow Ukraine to use U.S.-supplied ATACMS for strikes inside Russia, Seoul's presidential office said Monday. When asked whether Washington had shared information ahead of its authorization for the use of the missile system, a senior presidential official told reporters on the margins of the G20 summit in Rio de Janeiro, Brazil, on Monday, that Seoul has been "notified of the U.S. decision." The surface-to-surface ballistic missiles, fueled by solid rocket propellant, are manufactured by Lockheed Martin and have a range of approximately 300 kilometers (186 miles). The presidential official said that South Korea has made no decision regarding providing lethal arms to Ukraine, though President Yoon Suk Yeol has previously indicated that Seoul could consider the possibility depending on the development of military ties between Pyongyang and Moscow. Kyiv's missile strike came as Russia's war on Ukraine marked its 1,000th day, and shows a significant shift in policy from the outgoing Biden administration before U.S. President-elect Donald Trump takes office in two months. Trump, in turn, signaled during his campaign that he was keen on swiftly ending the war, prompting concerns from NATO countries that this could lead to significant Ukrainian concessions. Russian Foreign Minister Sergei Lavrov, who attended the G20 summit instead of Putin, told reporters in Rio de Janeiro Tuesday that Ukraine's "multiple use of ATACMS in the Bryansk region last night signals a desire for escalation," adding that utilizing such "sophisticated missiles without American involvement is unfeasible." The U.S. embassy in Kyiv, in turn, temporarily shuttered its doors after being warned on Wednesday of a "potential significant air attack" after Russia vowed to respond after Ukraine's missile strike. The embassy said in a statement that "out of an abundance of caution," its doors will be closed and staff have been instructed to shelter in place, while recommending U.S. nationals to "be prepared to immediately shelter in the event an air alert is announced." South Korea's National Intelligence Service (NIS) briefed lawmakers on the situation regarding Ukraine's missile launch on Russia on Wednesday, and Democratic Party Rep. Park Sun-won told reporters afterward that Putin's revision of his country's nuclear doctrine "sends a