U.S. President Donald Trump on Sunday criticized North Korean leader Kim Jong Un, saying he was "acting very, very badly", reported the Reuters news agency.
Trump’s comments to reporters were made as he departed his Mar-a-Lago resort in Florida, where he spent the weekend.
The President said administration officials had meetings during the weekend about North Korea, among other issues.
His comments came hours after North Korea tested a powerful new rocket engine, a test hailed by Kim as a "new birth" for the nation's rocket industry.
The test occurred two weeks after Pyongyang fired ballistic missiles into the sea off Japan's northwest coast.
The country’s official news agency later claimed the firing was a training exercise for a strike on American bases in Japan, adding that Kim personally supervised the drill.
Sunday’s test appeared to be timed to coincide with the visit of U.S. Secretary of State Rex Tillerson to Beijing on Saturday, where he warned that regional tensions had reached a "dangerous level".
During the visit, the U.S. and China pledged to work together to address the threat posed by North Korea's nuclear program.
On Thursday, Tillerson visited Japan, where he hinted that Washington would take a tougher strategy to confront North Korea's nuclear threat, but also stressed Pyongyang had no need to fear the United States.
Tillerson’s comments were made after Pyongyang threatened to launch a series of "merciless" attacks on the U.S. if a U.S. Navy carrier violates its “sovereignty and dignity”.