WASHINGTON - The US military on Monday left open the possibility of additional North Korean ballistic missile launch attempts beyond the four medium-range missiles that landed in the sea off northwest Japan."There were four that landed. There may be a higher number of launches that we're not commenting on. But four landed and splashed in the Sea of Japan," Navy Captain Jeff Davis, a Pentagon spokesman, told a news briefing.Reuters reported on Sunday that the United States saw no indications of an intercontinental ballistic missile launch. Davis confirmed on Monday that there was no ICBM launch attempt.