Seoul 's defense ministry said two bullets crashed about 150 meters from the South Korean Navy corvette patrolling the tense western sea border on Thursday .
The ship was not damaged and responded by firing five shells into waters near the North Korean military ship .
" The fact verified that naval ships puppet state , which is very barged into our waters under the pretext of controlling the fishing boat of China , opened fire haphazardly and lied that we had shot first . This is a hoax , " said Front Command West North Korea's military said in a statement .
( Read: budidaya kroto )
" All forces under the command of the Western Front are well prepared to destroy the cruel provocative actions performed by the puppet military gangsters on behalf of all the people" .
He said he then promised to change the tense sea border area into a "graveyard " for the South Korean Army .
The incident comes after a South Korean naval vessel fired warning shots on Tuesday , after three North Korean patrol boat crossed the sea border .
North Korea later Wednesday threatened to launch attacks against warships South Korea without the slightest warning from provocative actions , and claimed the North Korean patrol boat that control of illegal Chinese fishing boats in the disputed northern border .
North Korea does not recognize the Northern Limit Line as the sea border , drawn unilaterally by the United Nations in the Yellow Sea and the U.S. at the end of the Korean War .
The location was a short and bloody clashes between the navies of both countries in 1999 , 2002 and 2009 .
In March , the North fired hundreds of bullets in live ammunition drills near sea border .
About 100 shells fell into the territorial waters of South Korea , and Seoul reply with bullet shots into North Korean waters .
Cross- border tensions have been rising for months and both sides have upped their verbal cross on the discovery of a drone that crashed recently in the South Korean border .
Seoul said a joint investigation with U.S. analysts have provided evidence of "smoking gun " that the drone coming from the North .
Pyongyang emphatically denied the engagement .