WASHINGTON: President Joe Biden warned North Korea Thursday that the United States will "respond accordingly" if it escalates its military testing, after Pyongyang fired two missiles in its first major provocation since he took office.

The nuclear-armed North has a long history of using weapons tests to ramp up tensions, in a carefully calibrated process to try to forward its objectives.

Biden's response demonstrates a change of tone from his predecessor Donald Trump, who engaged in an extraordinary diplomatic bromance with North Korean leader Kim Jong Un and last year repeatedly played down similar short-range launches.

Pyongyang had been biding its time since the new administration took office, not even officially acknowledging its existence until last week.

But on Thursday it launched two weapons from its east coast into the Sea of Japan, known as the East Sea in Korea.

It was a violation of UN resolutions and the US was "consulting with our partners and allies," Biden said, warning North Korea that "there will be responses if they choose to escalate. We will respond accordingly."

"I'm also prepared for some form of diplomacy, but it has to be conditioned upon the end result of denuclearization," he told reporters.