The US military on Sunday continued preparations for annual military exercises with South Korea, DPA reported.
US defence officials told the Wall Street Journal that US F-22 stealth fighter jets arrived Sunday in South Korea for the joint exercises.
It is the latest demonstration of US military air power and comes three days after two US B-2 stealth bombers dropped dummy bombs onto a South Korean training ground near the North Korean border to demonstrate the US commitment to its allies in the region, the US military in Seoul said.
Relations between the parties have deteriorated since North Korea's third nuclear test on February 12, which led to a strengthening of international sanctions against it.
Pyongyang has since issued numerous threats, including on possible pre-emptive nuclear attacks.