About 8,000 North Korean troops in Russia are in the country’s Kursk border region and are expected to enter Moscow’s war with Ukraine in the “coming days,” Secretary of State Antony Blinken said Thursday. Russia has been training the North Koreans in artillery, basic infantry operations, drones and trench clearing, indicating “that they fully intend to use these forces in front-line operations,” he told reporters following a meeting with Defense Secretary Lloyd Austin and their South Korean counterparts in Washington, D.C.  “We've not yet seen these troops deploy into combat against Ukrainian forces, but we would expect that to happen in the coming days,” Blinken said, adding that if the North Korean troops enter the fight they would become legitimate military targets. The Pentagon earlier this week said about 10,000 North Korean soldiers were training in Russia and were seen outfitted in Kremlin uniforms and equipment en route to Kursk, where Ukrainian forces launched an incursion this summer. Blinken and Austin said Russian President Vladimir Putin’s reliance on the new troops is a sign the Kremlin is struggling in the fight. The U.S. has assessed the Russian military is suffering 1,200 casualties per day, more than at any time in the war.  “Putin has been throwing more Russians into a meat grinder of his own making in Ukraine. Now he's turning to North Korean troops, and that is a clear sign of weakness,” Blinken said. Austin, meanwhile, said the 10,000 North Korean soldiers assessed to be in Russia “won't come close” to replacing the numbers Moscow has lost.  During the meeting, the U.S. and South Korean officials discussed a range of options to respond to the development, and Blinken said Washington would announce new security assistance for Ukraine in the coming days. The group also agreed that China should do more to curb North Korea's provocative actions and to stop supporting Russia’s defense industrial base, Blinken said. The meeting between U.S. and South Korean officials comes after Pyongyang conducted its longest ever test flight of an intercontinental ballistic missile earlier Thursday. The weapon flew for about 86 minutes before crashing into the sea off Japan. North Korea called the missile the “world's most powerful strategic weapon,” and an “appropriate military action” against enemies. Seoul, meanwhile, warned that Pyongyang could be gaining missile technology from Moscow for sending its troops to fight in Ukraine.  Austin said it's early in the U.S. assessment of the launch, but they did not see any indication there was Russian involvement in the event.  He also called the launch “irresponsible” and urged North Korea to “cease and desist” its behavior.  South Korea and Japan have also condemned the launch, which Tokyo said reached an altitude of 4,350 miles and flew a distance of about 620 miles.