New analysis of satellite photos shows that North Korea is involved in “producing or modifying” long-range nuclear missiles that threaten the United States, according to NBC News. The commercial satellite images from Planet Labs show that a temporary factory that houses the launcher arm has expanded, according to Jeffrey Lewis, director of the East Asia Nonproliferation Program at the Middlebury Institute of International Studies. The new analysis arrives amid growing concern among U.S. military and intelligence officials that North Korea will conduct a long-range missile test in the next few days or weeks. “There is activity at a number of locations indicating that North Korea is laying the groundwork for an expansion of their ICBM program—more systems, more buildings, more capabilities,” Lewis said in a statement. North Korea halted nuclear and long-range missiles tests in 2017 after Kim Jong Un and President Trump engaged in diplomatic talks and two summit meetings, but his regime recently warned of a “Christmas Gift to the United States.” U.S. Air Force Gen. Charles Brown, head of Pacific Air Forces, said the “gift” could be “some kind of long-range ballistic missile.” Kim has reportedly visited the facility three times since August 2017. “An expansion of the plant increases its capability to produce trucks for both civilian and military use,” Lewis wrote.