Marines of the Republic of Korea (ROK) patrol along a barbed wire fence on Baengnyeongdo, an island near the disputed maritime border with the Democratic People's Republic of Korea (DPRK) where one of the ROK warships sank in March, August 5, 2010. Pyongyang threatened "physical retaliation" if the exercise went head, but analysts said chances of a military escalation were slim.[Agencies]