In a move likely watched closely by Japan, the U.S. military has begun issuing furlough warnings to almost 9,000 civilian South Korean employees as Washington and Seoul remain at loggerheads over President Donald Trump's demand that its ally pay more for its hosting of American troops.

The notices inform workers at American military facilities in South Korea that they potentially face administrative furloughs as of April 1, according to a statement issued Wednesday by U.S. Forces Korea.

The two sides remain deadlocked, although U.S. officials have indicated they have backed off Trump's initial demand that South Korea pay about $5 billion a year for U.S. forces stationed there — more than five times the $900 million in a stopgap one-year agreement that expired on Dec. 31. South Korea has said there is quite "a big difference in principle" between the two sides.