South Korea carried out live-fire drills near its western border islands Monday, despite North Korea\'\'s strong threats of retaliatory strikes. The drills took place in waters near Baengnyeong and Yeonpyeong islands, located just south of the tense Yellow Sea border with North Korea. They came a day after the North\'\'s military vowed to \"promptly make merciless strikes\" if the South violates its territorial waters, reported South Korean news agency (Yonhap). \"We had our routine maritime firing drills for about two hours starting 9:30 a.m.,\" an official with the Joint Chiefs of Staff (JCS) said. \"These were designed to test our weapons at Marine Corps units on the Yellow Sea and also to maintain our military\'\'s combat readiness in the area.\" The Joint Chiefs of Staff said the North had placed its armed forces on heightened alert during the South\'\'s exercises, but that it had detected no unusual movement from north of the border. The official KCNA news agency had quoted the North\'\'s military saying that if the South \"starts a reckless military provocation in those waters, trespassing on the Democratic People\'\'s Republic of Korea\'\'s inviolable marine demarcation line,.... the Korean People\'\'s Army will promptly make merciless retaliatory strikes.\" While the drills were underway, the Unification Ministry, which handles inter-Korean affairs in Seoul, said the North had trespassed its boundaries with its warning. \"It is inappropriate for North Korea to talk about our routine exercises in such fashion,\" said ministry spokesman Kim Hyung-suk in a press briefing. \"The drills were held within our territorial waters to ensure our national security.\"