Analysts and security officials say they are watching for signs that North Korea may use an upcoming holiday to unveil new weapons or test fire a submarine-launched ballistic missile (SLBM), after a flurry of activity was detected at a key base.

Formations of troops have been seen practicing for what is expected to be a major military parade on Oct. 10, the 75th anniversary of the ruling Workers’ Party of Korea. Some observers say North Korea may showcase its largest missiles for the first time since 2018.

Imagery analysts and security officials caution that so far there is no conclusive evidence of an impending launch. But after several typhoons lashed North Korea in early September, satellite photos have shown a flurry of activity at the Sinpo South Shipyard, including in a secure basin where a barge used in previous underwater missile launches is docked.

"We're monitoring developments, as there is a possibility that a submarine-launched ballistic missile test will be conducted there using ejection equipment shortly after the repair is done," Won In-choul, the nominee for chairman of South Korea's Joint Chiefs of Staff, told lawmakers this week.