SEOUL (Reuters) - South Korea is questioning four North Koreans rescued from waters off the east coast and will return them to the North if they want to go back, the South’s Unification Ministry said on Monday.

Koreans from the reclusive and impoverished North have occasionally defected to the rich, democratic South by fishing boat, crossing the disputed maritime border between the two sides, but most defections are via China.

The four North Koreans were found on two vessels on Friday and Saturday by the South Korean navy, the ministry said.

“They are currently under investigation and will be asked whether they want to go back to the North,” Unification Ministry spokesman Lee Duk-haeng told reporters.

The rescue comes days after South Korea returned six North Korean fishermen rescued from straying fishing boats.

North and South Korea remain in a technical state of war since their 1950-53 conflict ended in a truce, not a peace treaty.

The U.N. Security Council on Friday expanded targeted sanctions against North Korea after its repeated missile tests, adopting the first such resolution agreed by the United States and the North’s only major ally, China, since U.S. President Donald Trump took office.

The North regularly threatens to destroy the United States and says its missile and nuclear programs are needed to counter U.S. aggression.