A ruling Chinese Communist Party newspaper is warning North Korea against conducting another nuclear test, saying that would likely propel events past the "point of no return".
Trump spoke by phone with both the Japanese and Chinese leaders Monday.
In March, the North's state media reported that the country successfully conducted a ground test of a new high-thrust rocket engine, which it said was a breakthrough for the country's space program and efforts to create "Korean-style strategic weapons". "All stakeholders will bear the consequences, with Pyongyang sure to suffer the greatest losses".
North Korea's growing nuclear and missile threat is perhaps the most serious security challenge confronting US President Donald Trump.
However, Beijing is intensely wary of any measures that might cause the collapse of North Korean leader Kim Jong Un's hard-line communist regime, fearing that could lead to a wave of refugees and a Pyongyang government beholden to Washington and Seoul.
South Korea's envoy for North Korea Kim Hong-kyun says he and his Japanese and American counterparts have agreed to "maximize pressure" on North Korea to prevent it from making further provocations. She praised China's increased pressure on North Korea.
The North held a meeting on Monday to celebrate the KPA's anniversary, stressing that it is ready to respond to possible Washington military actions.
Yun says China especially has "a very, very important role" to play.
Trump yesterday urged the UN Security Council to consider stronger sanctions against Pyongyang.
Commercial satellite imagery suggests the North has been readying for weeks for an underground atomic explosion, and could conduct one at any time.
Kishida also said he plans to attend a U.N. Security Council meeting to be held in NY on Friday that will focus on how to denuclearize North Korea. South Korean Prime Minister Hwang Kyo-ahn, the country's acting leader, has instructed his military to strengthen its "immediate response posture" in case North Korea does something significant on Tuesday's anniversary.
Kim reported from Seoul, South Korea.
The JoongAng Ilbo daily said in an editorial that South Korea shouldn't be excluded from critical discussions surrounding North Korea, because "the destiny of our nation could be at stake".
However, South Korea's military said it was closely watching North Korean troop movement around an eastern coastal town where the North reportedly conducted a huge live-fire drill to mark the holiday.
The Michigan is one of the largest submarines in the United States' arsenal and its tomahawk missiles have a range of 1,600km, meaning that from Busan the submarine could hit North Korean ports or military installations.
North Korea often marks significant dates with show of military capability, and South Korean officials have said the North could be preparing another round of nuclear or missile tests around the anniversary.
Trump has said the United States was sending an "armada" to the Korean peninsula, including submarines.
The Michigan's visit to Busan comes after North Korea on Sunday threatened to sink the American aircraft carrier USS Carl Vinson, which is beginning joint drills with two Japanese destroyers in the western Pacific Ocean.
While Trump has dispatched what he called an "armada" of ships to the region, including an aircraft carrier, US officials have told The Associated Press that the administration doesn't intend to militarily respond to a North Korean nuclear or missile test.
Japan's envoy on North Korea, Kenji Kanasugi, said after talks with his US and South Korean counterparts that they all agreed China should take a concrete role to resolve the crisis and it could use an oil embargo as a tool to press the North.
North Korea, which conducted two nuclear tests and test-fired more than 20 ballistic missiles previous year alone in defiance of U.N. Security Council resolutions, Japanese officials said.
On April 15, North Korea offered a fresh look at its advancing nuclear weapons and missiles program in a massive military parade in Pyongyang honoring late state founder Kim Il Sung, the grandfather of the current ruler. Japan's Chief Cabinet Secretary Yoshihide Suga told reporters that the three envoys were to deepen cooperation and ensure their countries stay on the same page amid growing tension.
Japan's Foreign Ministry also announced that China's envoy for North Korea, Wu Dawei, will visit Tokyo later Tuesday for talks with Kanasugi.
South Korean and USA officials have feared for some time that a sixth North Korean nuclear test or the latest in a string of missile launches could be imminent.
Chief nuclear negotiators from left to right, Joseph Yun, U.S. special representative for North Korea policy, Kenji Kanasugi, director general of the Japanese Foreign Ministry's Asian and Oceanian Affairs Bureau, and Kim Hong-kyun, special representative for Korean Peninsula peace and security affairs at the South Korean Foreign Ministry, join hands before their meeting about North Korean issues at the Iikura Guesthouse in Tokyo on Tuesday, April 25, 2017.
North Korea's leader Kim Jong Un did not attend.