North Korea warned on Saturday it could take physical action against South Korea in response to the South''s "ceaseless provocative war moves." The warning came as activists in South Korea opposed to the secretive regime plan to float balloons carrying the leaflets across the border in time for the 66th anniversary of the North''s ruling communist party inauguration on Monday. "The north side reminds the south side once again that the army and people of the DPRK (North Korea) are compelled to make a physical retaliation against the south side''s ceaseless provocative war moves," a statement released by Pyongyang''s official Korean Central News Agency said Saturday. "In September alone, more than 80 warships of the South Korean navy intruded into the waters of the North side in the sea, while anti-communist right-wing conservative organizations scattered a lot of leaflets and undesirable USBs and pamphlets into areas of the north side of the border". The disputed sea border in the Yellow Sea has been a flashpoint where bloody naval clashes erupted between the two sides in 1999 and 2002 and navies of the two sides exchanged fire in 2009. A week earlier, North Korea blasted the South for broadcasting propaganda on loud speakers across the border, warning of "merciless punishment" by the army against if the campaign persisted.