Japan put its military on alert on Monday for a possible North Korean ballistic missile firing, while South Korea also said it had detected evidence of launch preparations, officials from Japan and South Korea said.
Tension in the region has been high since North Korea conducted its fourth nuclear test in January and followed that with a satellite launch and test launches of various missiles.
Japan ordered naval destroyers and Patriot anti-ballistic missile batteries to be ready to shoot down any projectile heading for the country, state broadcaster NHK said.
A Japanese official, who declined to be identified as he is not authorized to speak to the media, confirmed the order. A spokesmen for Japan's defense ministry declined to comment.