Japan is on full alert ahead of an expected mid-range missile launch by North Korea, its defence minister said Wednesday as South Korea raised its military watch alert to "vital threat".
"We have been on full alert since we deployed military units, and so we will maintain this sense of vigilance," Defence Minister Itsunori Onodera told reporters.
Prime Minister Shinzo Abe separately said: "We are making utmost efforts to protect our people's lives and ensure their safety."
The South Korea-US Combined Forces Command raised its "Watchcon" status from 3 to 2 reflecting indications of a "vital threat", Yonhap news agency said, citing a senior military official.
South Korean intelligence says the North has prepared two mid-range missiles for imminent launch from its east coast, despite warnings from ally China to avoid provocative moves at a time of soaring military tensions.
Japan, where the armed forces have been authorised to shoot down any North Korean missile headed towards its territory, Tuesday stationed Patriot missiles in its capital to protect the 30 million people who live there.
In addition to PAC-3 batteries, Aegis destroyers equipped with sea-based interceptor missiles have been deployed in the Sea of Japan (East Sea).
Pyongyang's bellicose rhetoric has reached fever pitch in recent weeks, with near-daily threats of attacks on US military bases including in Japan and South Korea in response to ongoing South Korean-US military exercises.
A top US military commander said Tuesday that he favoured shooting down a North Korean missile only if it threatened the United States or Washington's allies in the region.
Analysts said Tokyo's measures were purely precautionary and a mis-targeted missile that might end up falling uncontrollably towards Japanese territory was most likely what Tokyo was readying for.