SEOUL-North Korea fired two short-range ballistic missiles on Wednesday, Seoul’s military said, just days after Pyongyang’s last test and ahead of a visit to South Korea by US Vice President Kamala Harris.

The launches, part of a record-breaking blitz of weapons tests this year by North Korea, came after Seoul’s spy agency warned that Pyongyang was close to conducting another nuclear test.

South Korea’s military said it had “detected two short-range ballistic missiles fired from the Sunan area in Pyongyang”.

“Our military has reinforced monitoring and surveillance and is maintaining utmost readiness in close coordination with the United States,” Seoul’s Joint Chiefs of Staff said in a statement. Japan’s coast guard also identified a possible ballistic missile launch, citing information from Tokyo’s defence ministry, and warned ships to be aware. The latest launch comes after North Korea test-fired a short-range ballistic missile on Sunday. Harris is due to arrive in Seoul on Thursday for a brief visit, during which she will go to the heavily fortified border between North and South Korea. The White House has said Harris’ visit intends to underscore the importance of the alliance with Seoul.

Washington is Seoul’s key security ally and stations about 28,500 troops in South Korea to help protect it from the North.