Japan is readying its defences ahead of a planned rocket launch by North Korea next month.
Defence minister Naoki Tanaka said he has ordered the deployment of anti-missile ships to shoot down any rockets fired.
The move by the Japanese government comes as world leaders prepare to meet in Seoul for a summit officially focused on nuclear terrorism.
North Korea’s nuclear ambitions are expected to feature high on the agenda at the talks on Monday and Tuesday in the South Korean capital.
Pyongyang said last week that it will carry out a rocket-powered satellite launch in mid-April.
South Korea and its allies believe the project is a precursor to a long-range missile test.
The United States has warned the launch would put a food aid deal at risk that was agreed with Pyongyang in early March.