Envoys from the US, Japan and South Korea met in Tokyo, with a senior Chinese official due to arrive later in the day.

North Korea often marks significant dates by displaying its military capability and has conducted five nuclear tests. Pyongyang launched a missile one day after the 105th birthday of late founder Kim Il Sung on April 15.

However the morning came and went without any nuclear tests or ballistic missile launches, and all that was publicly scheduled for the day were gatherings for mass dancing, a common celebration on major North Korean holidays.

A "national meeting" of thousands of senior military and civilian officials was held the day before, although North Korean leader Kim Jong Un did not attend.

His minister of defence General Pak Yong Sik told the event that the country is ready to use pre-emptive strikes or any other measures it deems necessary to defend itself against the "US imperialists".

He said: "The situation prevailing on the Korean peninsula is so tense that a nuclear war may break out due to the frantic war drills of the US imperialists and their vassal forces for aggression."

Any missile test could test the North Korea policies of President Donald Trump, who has reportedly settled on a strategy that emphasises increased pressure on Pyongyang with the help of China, the North's only major ally.

He has reportedly rejected military options or trying to overthrow North Korea's government.

The nuclear-powered USS Michigan submarine arrived at Busan in what was described as a routine port visit to rest the crew and load supplies.

The submarine's arrival comes as the USS Carl Vinson aircraft carrier heads toward the Korean Peninsula in a show of force.

In Tokyo, US representative for North Korea policy Joseph Yun was meeting his Japanese counterpart Kenji Kanasugi and Kim Hong-kyun of South Korea.

Japan's foreign ministry announced that China's envoy for North Korea, Wu Dawei, will visit Tokyo on Tuesday for talks with Mr Kanasugi.

Mr Trump spoke by phone with both the Japanese and Chinese leaders on Monday.

Chinese state broadcaster CCTV quoted President Xi Jinping as telling Mr Trump that China strongly opposes North Korea's nuclear weapons programme and hopes "all parties will exercise restraint and avoid aggravating the situation".

Prime Minister Shinzo Abe of Japan and Mr Trump agreed to urge North Korea to refrain from what Mr Abe called provocative actions.

"The North Korean nuclear and missile problem is an extremely serious security threat to not only the international community but also our country," the Japanese leader told reporters in Tokyo afterwards.

Recent US commercial satellite images indicate increased activity around North Korea's nuclear test site, and third-generation dictator Mr Kim has said the country's preparation for an ICBM launch is in its "final stage".

Adding to the tensions, North Korea detained a US citizen on Saturday, bringing the number of Americans being held there to three.

The reasons for the detention of Tony Kim, who taught accounting at the Pyongyang University of Science and Technology, were not immediately clear.

Under Kim's leadership, North Korea has been aggressively pursuing a decades-long goal of putting a nuclear warhead on an ICBM capable of reaching the US mainland.

Last year, North Korea conducted two nuclear tests, which would have improved its knowledge in making nuclear weapons small enough to fit on long-range missiles.

It also launched a long-range rocket last year that delivered a satellite into orbit, which Washington, Seoul and others saw as a banned test of missile technology.