The United States has extended for another year a travel ban on North Korea for American citizens.

The State Department announced on Monday that the ban will remain in place until August 31 next year unless revoked by Secretary of State Mike Pompeo.

In a notice that will be published in the Federal Register on Tuesday, the department said it determined that there continues to be “a serious risk” that U.S. nationals may be arrested and subject to long-term detention in the North.

The travel ban was first imposed in September 2017 and renewed in 2018. The U.S. introduced the measure in the wake of the death of Otto Warmbier, an American college student who was detained in the North and died shortly after being released to U.S. authorities in a comatose state.

The Associated Press said that the ban allows certain categories of American citizens such as aid workers or journalists to obtain a special validation passport good for one trip to North Korea.