North Korea said Friday it test-launched new anti-aircraft missiles, as its military threatened unspecified grave steps against the U.S. and South Korea over their joint military drills that it views as an invasion rehearsal.

The official Korean Central News Agency said leader Kim Jong Un oversaw the tests and called the missiles ‘another major defence weapons system’.

North Korea successfully test-fired a new anti-aircraft missile system, state-run media reported Friday, as Pyongyang continued to condemn U.S.-South Korea joint military drills.