Japan has put its forces on high alert as tensions on the Korean are near breaking point.
According to Japanese government officials, it is important to remain on high alert incase of a contingency.
The Public Security Intelligence Agency has credible information that North Korea is ready for war and a serious confrontation with Seoul is within weeks.
Japan has also confirmed that Pyongyang has recalled thousands of its citizens in Russia back to the country in readiness for war.
The authenticity of these North Koreans is in doubt and it is feared they are Russian trained commandos.
Over 50,000 Koreans work in Russia, a key Pyongyang ally. North Korea fired hundreds of shells into a fishing Island of South Korea killing two Seoul Marines and two civilians.
Japans cabinet has met to deliberate on the course of action the country would take incase of a preemptive contingency on its soil if a confrontation is triggered this weekend or in the coming days.
US naval ships and fighter jet carriers have arrived in the Yellow sea for a joint military drill with its ally South Korea, something North Korea terms as an aggression.
Pyongyang has promised retaliation if provoked.
The country, which is highly militarized, could become destroyed if the US decides to use brutal fore to punish its deviant regime led by Kim Jong II.
Japan has been on the lead to condemn North Korea, which is armed and economically propped by China, Japans arch rival.
In Seoul, military supporters are condemning the government for being toothless after being attacked by Pyongyang on Tuesday.
Protesters insist the government respond to the attacks in an aggressive manner.