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.
The missile tubes on a Patriot missile battery on the grounds of Japan's Ministry of Defense were elevated to a firing position.
The South Korean defense official declined to comment on what type of missile might be launched, but South Korea's Yonhap News Agency said officials believe it would be an intermediate-range Musudan missile.
"We've detected a sign and are tracking that. We are fully prepared," said the South Korean official, who also declined to be identified.