The latest figures being bandied around Washington are that 10,000 North Koreans will be involved in a 50,000-strong force used by Russia to reclaim a sliver of land in its Kursk region seized by Ukraine earlier this year.
This area of southern Russia is where Ukraine has been granted permission to use the Atacms system.
George Barros, a researcher with the US-based Institute for the Study of War, believes this is critical to the decision to allow use of the missiles.
“I think the introduction of the North Koreans and the transition to the new administration are two important catalysing factors here that probably changed the administration policy,” he said.
What part — if any — Mr Trump played at the White House transition meeting remains under wraps for now.