U.S. Indo-Pacific Command chief Adm. John Aquilino is making arrangements to travel to Japan and South Korea next week to meet with government and military officials, a source familiar with the plan has said, with the trip taking place amid North Korea's repeated missile provocations.

Aquilino is likely to visit Japan in the first half of next week, the source said Friday. U.S. Vice President Kamala Harris has just returned from her trip to the two closest U.S. allies in Asia.

Since the start of this year, North Korea has test-fired missiles on more than 20 occasions, including on Saturday, when it fired off two short-range ballistic missiles into the Sea of Japan.

Concerns linger that North Korea could soon carry out its seventh nuclear test, which would be its first since September 2017.

Tensions have also grown over Taiwan following China's increased military activities in the area in response to U.S. House of Representatives Speaker Nancy Pelosi's visit to the self-ruled island in early August.