SEOUL (Reuters) - U.S. President Donald Trump discussed plans to respond to North Korea’s recent missile launches with South Korea’s acting president Hwang Kyo-ahn, an official at Hwang’s office said.

Trump also had a phone call with Japanese Prime Minister Shinzo Abe on Tuesday, reaffirming its alliance with Tokyo and condemning North Korea’s tests as a threat to regional security.

North Korea fired four ballistic missiles into the sea off Japan’s northwest on Monday, angering South Korea and Japan.