The South Korea- U.S. Combined Command Forces raised the watch level against the Democratic People's Republic of Korea (DPRK) by one notch on Thursday, South Korea's Yonhap News Agency reported, citing an official.

According to South Korean defense spokesman Won Tae-jae, the Combined Forces raised the Watchcon system, the process of changing the reconnaissance posture for strategic and tactical warning of attack, at local time 07:15 Thursday (2215 GMT) from Level 3 to Level 2.

The second level of the five-stage surveillance system marks " vital indications of threat," under which the South Korean and U.S. forces are to step up their intelligence-collection activities.

Meanwhile, the five-stage alerting procedure, "Defcon," remains at four, which refers to "Normal, with increased intelligence and strengthened security measures," the official said.

Unlike the Watchcon system, a measure of the surveillance level, the Defcon, or Defense Readiness Condition, is a measure of the activation and readiness level, and matched to the situations of military severity.

The recent decision marks the first elevation in the Watchcon since October 2006 when the DPRK conducted its first nuclear test and the fifth since the 1953 Korean War Armistice Agreement

On the other hand, the Defcon has been fixed at Level 4 ever since the armistice.

The Watchcon raise came amid increased military tensions on the Korean Peninsula as the DPRK conducted a nuclear test on Monday, followed by continuous military threats with several short-range missile firings.

South Korea reacted with announcing its full participation in a U.S.-led nonproliferation campaign, which the DPRK had warned to be regarded as a declaration of war.

(Xinhua News Agency May 28, 2009)