The U.S. will kick off its annual joint military exercises with South Korea on Monday, but this year's drills will involve far fewer American troops than last year's amid heated tensions with nuclear-armed North Korea.

The Pentagon said Friday that the exercises, known as Ulchi Freedom Guardian (UFG), would see about 17,500 U.S. service members take part in the drills scheduled to begin Monday and run through Aug. 31.

About 25,000 were involved in the 2016 drills.