Vice President Mike Pence, however, is doing something about it, Reuters reports.
Pence is on a 10-day, four-nation tour of Asia, where he's meeting with longtime US allies South Korea and Japan.
Trump and Pence, who stopped at the Demilitarized Zone dividing North and South Korea on Monday, have signaled this week a forceful USA stance on North Korea's recent actions.
US President Donald Trump at a joint press conference with Italian Prime Minister Paolo Gentiloni. "We are with you 100%", he said.
In an interview in Wisconsin, the United States president complained that his predecessors should have dealt with North Korea's pursuit of a nuclear arsenal, but said he was in the position now where he was "going to have to do something about it".
"I truly don't believe North Korea is really prepared to engage in a proper war with the United States, as much as they might posture and claim that they can", he said.
Late previous year, China, which is believed to be the only country buying North Korean coal, announced it would slash its imports in line with global sanctions after a ballistic missile test.
After meeting with Abe, Pence held talks with Japanese Deputy Prime Minister Taro Aso on a new U.S. -Japan "economic dialogue" to be led by the two.
"We should stay on our toes to protect our territory and people's lives", Hwang said.
The singing was followed by footage of its test-firing of a missile in February which, in the video, was joined by other missiles shooting into sky, passing over the Pacific and exploding in giant balls of flames in the United States.
United States experts believe that only China has sufficient economic and political leverage to restrain Pyongyang's drive to develop a long-range missile capable of hitting the United States mainland with a nuclear warhead.
"Thermonuclear war may break out at any moment on the peninsula", Kim In Ryong threatened.
But it's becoming increasingly clear that President Trump might not know the name of North Korea's leader.
The Trump White House says previous administrations have tried to buy off rogue regimes with nuclear ambitions.
Said Abe: "It goes without saying that it is a matter of paramount importance for us to seek diplomatic efforts as well as peaceable settlements of the issue".
The last vice president to visit the Reagan was Joe Biden in 2009, Navy officials said. Foreign Ministry spokesman Lu Kang said tensions need to be eased on the Korean Peninsula to bring the escalating dispute to a peaceful resolution.
"[North Korea] is on a path to achieving nuclear weapons capability and we believe Kim Jong-un has a clear ambition to develop an intercontinental ballistic missile capable of carrying a nuclear payload as far as the United States", she told AM.
In Beijing, Chinese Foreign Minister Wang Yi made a new appeal Tuesday for calm on the Korean Peninsula.
A US official said the projectile "blew up nearly immediately", adding the type of missile North Korea was testing was still being assessed.
While Japan's trade surplus with the U.S.is much smaller than China's, Trump has decried the imbalance, especially in auto exports.
"China, if it wishes to, it can cut off North Korea's economic lifeline to the world", he told ABC radio on Wednesday.
China banned imports of North Korean coal, its most important export, in February, and Chinese media have raised the possibility of restricting oil shipments to the North.