The U.S. and South Korea began on Monday their biggest joint military exercise in about five years, after a hiatus on large-scale drills failed to entice North Korea’s Kim Jong Un to make concessions in disarmament talks.

The drills, known as Ulchi Freedom Shield, are expected to involve thousands of military personnel, and will run for two weeks. The U.S. and South Korea have said they are defensive in nature and will include exercises to coordinate forces in response to an invasion from North Korea.

An angry response is almost certain from North Korea, which for decades has assailed joint exercises as a prelude to invasion and nuclear war. Pyongyang has turned up the heat in its rhetoric in the past few weeks, indicating it could get back to the provocations that were largely put on hold as it battled a COVID-19 outbreak first revealed in May, and which it said ended earlier this month.