|The joint exercises come amid growing tensions following North Korea's deadly attack on South Korean island [Getty]
Japan and the US have launched one of their biggest ever joint military exercises in a show of force, just days after the United States and South Korea conducted smaller exercises aimed at deterring an aggressive North Korea.
The annual "Keen Sword" drills, which began on Friday, mark the 50th anniversary of the Japanese-US alliance and come amid growing Asia-Pacific regional tensions triggered by Pyongyang's artillery strike on a South Korean border island over a week ago that left four people dead.
Around 44,000 military personnel, 60 warships and 400 aircraft from both countries are taking part in the eight-day series of drills off Japan's southern islands.
The manoeuvres include integrated air and missile defence, base security, close air support, live-fire training, maritime defence and search and rescue.
The Pacific allies are for the first time being joined by South Korean military observers, in a bid by Tokyo to demonstrate solidarity among the three countries at a time of high tension in the region.
It follows Japan's sending of observers to take part in joint US-South Korean military exercises in July,
held after the sinking of the Cheonan, a 1,200-tonne South Korean naval vessel.
An international investigation blamed North Korea for the sinking, which left 46 South Korean sailors dead.
Japan, which relies heavily on the United States for its national security under its pacifist constitution, has been on high alert since the North Korean attack on Yeonpyeong island on November 23.
Meanwhile, China, North Korea's only major ally, criticised the military manoeuvres, saying to talk with the nuclear-armed North was better than to "brandish weapons".
"Those who brandish weapons are seen to be justified, yet China is criticised for calling for talks. Is that justified?," China's foreign ministry said in a statement.
However, Washington, Tokyo and Seoul snubbed Beijing's proposal for six-way crisis talks, instead scheduling their own three-way foreign ministers' talks in the US capital next Monday.
South Korea's foreign ministry said the talks would focus on the shelling of Yeonpyeong and include North Korea's nuclear advances.
The South is scheduled to hold further live-fire drills next week.