By Chris Hogg
BBC News, Tokyo
A new defence ministry is beginning operations in Japan, the first time such a ministry has been created since the country's defeat in World War II.
Japan's troops have started to join international missions
Japan's Self-Defence Forces, as they are known, were previously administered by a defence agency with a lower standing than fully-fledged ministries.
The government says the change will enable the troops to respond to "a change in the security environment".
But the country's pacifist constitution still forbids it from waging war.
Even though ministers want parts of that document re-written, there is no suggestion that the country's pacifist stance will be changed.
Japan's Prime Minister Shinzo Abe made the creation of a new defence ministry a priority for his administration when he took office late last year.
It is part of his efforts to make Japan more assertive on the world stage, with a military able to take part in peacekeeping missions overseas.
The man who will be the new defence minister says it is a response to the greater level of threat Japan faces.
In the past the deployment of troops abroad, such as the efforts to support the coalition in Iraq, required parliamentary approval for what were known as "extraordinary missions".
Now the law has been updated to list activities such as peacekeeping or international relief as the primary missions of the self-defence forces.
That means that in future Japan's parliament would not have to agree before troops are sent overseas.
That is why some of Japan's critics have expressed concern about a move they say could have a far-reaching effect on the country's future military development.
Japan's $41bn defence budget already gives it one of the most powerful military forces in the world.