WASHINGTON/BRUSSELS  -  The United States will not impose new limits on Ukraine’s use of American weapons if North Korea enters the fight, the Pentagon said on Monday, as NATO said North Korean military units had been deployed to Russia’s Kursk region. The North Korea deployment is fanning Western concerns that the 2-1/2-year conflict in Ukraine could widen, even as attention shifts to the Middle East. It could be a sign of how Russia hopes to offset mounting battlefield losses and continue making slow, steady gains in eastern Ukraine. “The deepening military cooperation between Russia and North Korea is a threat to both Indo-Pacific and Euro-Atlantic security,” NATO Secretary-General Mark Rutte told reporters after talks with a South Korean delegation about the North Korean deployments. U.S. President Joe Biden said the development was “very dangerous.” The Pentagon estimated 10,000 North Korean troops had been deployed to eastern Russia for training, up from an estimate of 3,000 troops last Wednesday.