SEOUL, Nov 5 (Reuters) - North Korea fired four short-range ballistic missiles into the western sea on Saturday, South Korea's military said, as Seoul and Washington ended a high-profile six-day military exercise.North Korea has launched a series of missiles this week, including a possible failed intercontinental ballistic missile, drawing condemnation from the United States, South Korea and Japan, and raising speculation it could be preparing to resume nuclear weapons testing for the first time since 2017.This is the first time the B-1B has been deployed in U.S.-South Korean drills since 2017, showing "the combined defence capabilities and determination of the Republic of Korea and the U.S. to resolutely respond to any provocations from North Korea, and the will of the U.S. to implement a strong commitment to extended deterrence," the joint chiefs said in a statement.As the tit-for-that exchange continued through the week, Washington called for a public United Nations Security Council meeting on Friday, where it accused Russia and China of providing "blanket protection" to North Korea from further Security Council action.A North Korean foreign ministry spokesman issued a statement late on Friday warning that "sustained provocation is bound to be followed by sustained counteraction," said state media KCNA."