firings come amid heightened tensions on the Korean peninsula . North Korea conducted a nuclear test in May , fired test rockets and threatened U.S. and South Korean ships near its territorial waters . Watch S. Korea confirm firing of missiles '' The first two missiles were fired about 8 a.m. and 8:30 a.m. , Yonhap reported . Another missile was launched about 10:45 a.m. , the agency reported . A fourth one came some time after that . The U.S. Navy and other U.S. officials said they are ready to track any missiles . `` The United States is aware of possible missile launches by North Korea . We are closely monitoring North Korea 's activities and intentions , '' a U.S. official said . `` This type of North Korea behavior is not helpful . What North Korea needs to do is fulfill its international obligations and commitments . '' Earlier this week analyst Daniel Pinkston said the reported test might be training for a future test but it could also just be a routine military exercise . `` It is worrisome to some degree , but it is different from a ballistic missile launch , '' said
SEOUL , South Korea -LRB- CNN -RRB- -- North Korea fired several short-range missiles toward the Sea of Japan on Saturday , an act that the U.S. watched closely and South Korea called provocative . N. Korean army soldiers , back , look at a S. Korean soldier , center , in the demilitarized zone in June . Pyongyang fired six short-range missiles in less than seven hours , South Korea 's Foreign Ministry said . The missiles were apparently Scud-type , estimated to have a range of about 500 kilometers -LRB- 310 miles -RRB- , according to South Korea 's Yonhap news agency . South Korean intelligence estimates that North Korea has about 700 such missiles in its arsenal . Pyongyang test-fired four such missiles off the east coast Thursday , Yonhap reported . South Korea called the launches a provocative act , according to a government statement . North Korea had issued a warning to mariners to avoid an area in the Sea of Japan at certain times between June 24 and July 9 because of a `` military firing exercise , '' according to a U.S. military communication about the warning provided to CNN . The recent