South Korean Defense Minister Kim Kwan-jin on Thursday urged key military commanders to stay alert against potential North Korean provocations, Yonhap News Agency reported.\"Over the past year, we have stressed that we will exercise our right to self-defense and sternly punish the enemy if it provokes us again,\" Kim was quoted as saying at a meeting of some 150 senior military officers, including Army Gen.Jung Seung-jo, Chairman of the Joint Chiefs of Staff (JCS), the chiefs of staff for the Army, the Navy and the Air Force and other key commanders. \"Our forces have transformed into combat-ready forces and I think this is the direction we have to take going forward.\" The South Korean military has beefed up its defense posture following two deadly North Korean attacks last year -- its torpedoing of the South Korean warship and its shelling of Yeonpyeong Island, both in the Yellow Sea. 50 South Koreans, including two civilians, were killed in the provocations.Kim said the year 2012 will be a critical one for security on the Korean Peninsula since South Korea, as well key allies such as the US, China and Russia, will all hold presidential elections. Also, North Korea has set out to become a powerful and prosperous nation in 2012.