Kuwait will expel North Korea’s ambassador to the oil-rich country and four other diplomats, potentially limiting Pyongyang’s ability to earn money for its nuclear program from laborers it sends to the Gulf.

The decision comes as Kuwait in recent weeks offered contradictory statements about its relationship with North Korea. The U.S. and Asian nations have increased pressure on their allies to cut ties as Pyongyang has tested a nuclear weapon and launched ballistic missiles over Japan.

North Korea’s Embassy in Kuwait City serves as its only diplomatic outpost in the Gulf. Pyongyang has thousands of laborers working in Kuwait, Oman, Qatar and the United Arab Emirates .

Responding to international pressure, Kuwait will expel Ambassador So Chang Sik and four other staffers. That will leave four diplomats at the embassy. The embassy did not respond to a request for comment.

A Gulf-based official confirmed on Sunday that Kuwait would be expelling the diplomats, speaking on condition of anonymity to discuss intelligence reports. A letter Kuwait sent in August to the United Nations also made that pledge.

Kuwait’s Information Ministry did not respond to a request for comment.

Kuwait’s ruling emir, Sheikh Sabah Al Ahmad Al Sabah, traveled to Washington and met with U.S. President Donald Trump this month. In a statement, the U.S. Embassy in Kuwait City called Kuwait “a key regional partner on [North Korea] and many other issues.”

“Kuwait has taken positive steps in regards to implementing U.N. resolutions related to” Pyongyang, it said.

While a small market compared to China and Russia, the amount of money North Korean laborers in the Gulf kick back to the government helps Pyongyang evade international sanctions, authorities say. A 2015 U.N. report suggested that the more than 50,000 North Koreans working overseas earned Pyongyang between $1.2 billion and $2.3 billion a year. Other estimates put earnings in the hundreds of millions of dollars.

The ongoing North Korea crisis is a tough one for Kuwait, a staunch American ally since the U.S.—led 1991 war that ended Iraqi dictator Saddam Hussein’s occupation of the country. Kuwait now hosts some 13,500 American troops.