President Trump wants South Korea to foot the bill for a $1 billion U.S. missile defense system and is threatening to kill the free trade deal between the two countries.

His comments aren't sitting well with officials in South Korea, a key American ally in Asia. One foreign policy expert called the remarks “shameless.”

“I informed South Korea it would be appropriate if they pay,” Trump said in an interview with Reuters on Thursday. “That's a billion dollar system.”

He was talking about the Terminal High Altitude Area Defense (THAAD) system, which is being deployed in South Korea in an effort to reduce the threat from North Korean missiles.

The THAAD deployment has already caused tensions inside South Korea and hurt the country's relations with China. Trump's comments are likely to further complicate the situation.

South Korean Defense Minister Han Min-koo has repeatedly said his country won't bear the cost of the system. His ministry stuck to that stance following Trump's remarks.

Washington and Seoul first announced plans for the deployment of the THAAD system in July, before Trump's election. The two countries have a mutual defense treaty, and more than 28,000 U.S. troops are stationed in South Korea.

On the campaign trail, Trump frequently said South Korea and other key U.S. allies should pay more for the defense provided by the U.S.

THAAD is unpopular among a significant portion of the South Korea public and has become a key issue ahead of the country's presidential election on May 9.

BDST: 1610 HRS, APR 28, 2017
AP