Why is Japan building up its navy?

As the balance of power in Asia swings towards China, Japan is building one of the most modern and powerful naval forces in the world.

In the aftermath of WWII, the US imposed a settlement on Japan, supposed to "cure" it of its war-making abilities.

In a new constitution, the country renounced war forever. But in 2013, Japan scrambled fighters 267 times to intercept incoming Chinese aircraft.

Rupert Wingfield-Hayes reports for Newsnight from Tokyo.