The Democratic People's Republic of Korea (DPRK) issued on Wednesday a second-in-one-day tough statement over South Korea's full participation in the U.S.-led Proliferation Security Initiative (PSI), warning to take "decisive measures."

If anyone attempts to stop, seize or check DPRK vessels, the DPRK will regard it as an intrusion into its territory and a violation of its sovereignty, and will make "decisive and merciless retaliation," a statement issued by the Committee for the Peaceful Reunification of Korea said, according to the official KCNA news agency.

The statement said that South Korea's participation in the PSI was a "declaration of war" against the DPRK, and that the DPRK would "take actual actions corresponding to the state of war."

It was the second tough statement that the DPRK has made in response to South Korea participating in the PSI in just one day. The DPRK military earlier made a three-point statement, warning to take military actions against South Korea and United States over land and water borders.

The PSI is designed to interdict the trade of weapons of mass destruction. South Korea became its 95th member after the DPRK said it successfully tested its second nuclear explosive device on Monday.

(Xinhua News Agency May 28, 2009)