North Korea's capital remained largely quiet on Monday, a day before the founding anniversary of its military, with residents in Pyongyang going about their business as usual despite heightened concerns elsewhere in the world over its nuclear and missile threats.

Major streets in the city have been decorated with national flags and signs to commemorate the 85th anniversary of the foundation of the Korean People's Army.

A meeting of hundreds of senior party and military officials for the 1.19 million-strong army was held, but without the attendance of leader Kim Jong Un, according to footage of it aired in the evening by the country's state-run Korean Central Television.

Pak Yong Sik, the country's defense minister, who delivered a speech, lauded Kim's leadership in bolstering its military capabilities and much of what he said during the so-called national meeting was adversarial toward the United States.

"As already has been declared, our revolutionary armed forces will completely rid the stronghold of aggression on the planet by a nuclear pre-emptive strike," if the United States and its allies resort to military adventurism, Pak said.

But there have been no reports or indications of a major event on Tuesday, other than ordinary citizens practicing for outdoor dancing festivities to be held in front of a gymnasium, a theater and several other public venues. 

Speculation has been rife that North Korea could conduct its sixth nuclear test or another launch of a ballistic missile around this occasion.

South Korean officials have said North Korea is technically ready to explode a nuclear device again at any time after it did so twice in 2016.

Reflecting the tense situation outside North Korea, U.S. President Donald Trump on Monday had phone conversations separately with Chinese President Xi Jinping and Japanese Prime Minister Shinzo Abe.

Trump agreed with the two Asian leaders to work closely in dealing with North Korea's defiant pursuit of nuclear weapons.

The Trump administration has also ordered a U.S. aircraft carrier and its strike group toward waters off the Korean Peninsula.

North Korea's official media have recently issued a series of reports decrying the dispatch of the USS Carl Vinson-led battle group, calling it a reckless action of aggression to aggravate the tensions in the region.