WASHINGTON (MarketWatch) — U.S. F-22 stealth fighter jets arrived in South Korea on Sunday for exercises as part of an effort to demonstrate advanced military capabilities, seeking to deter provocations from North Korea, according to reports.

The move come after North Korea warned South Korea earlier in the weekend that the Korean peninsula had entered a “state of war,” according to an Associated Press report. Pyongyang threatened to shut down a border factory that is a symbol of North and South Korean cooperation, according to the report.