Japanese PM Shinzo Abe has called for a review of the pacifist constitution imposed after World War II.
Japan's troops have started to join international missions
In a statement on the constitution's 60th anniversary, Mr Abe spoke of the need for a "new era" to allow Japan to take a larger role in global security.
Mr Abe, who came to office last year, has made revising the constitution one of his main priorities.
But critics in South Korea and China, which suffered at the hands of Japanese wartime forces, oppose the move.
Many pacifist elements also remain within Japan, and opinion polls show the public has mixed views about Mr Abe's aims.
A 'new Japan'
A military was formally banned in Japan when US occupation authorities wrote the country's constitution in the wake of WWII.
The document, which bans military force in settling international disputes and prohibits maintaining a military for warfare, has not been altered since 1947.
But in line with previous comments on the issue, Mr Abe used the anniversary of the constitution to call for a "bold review of Japan's post-war stance and an in-depth discussion of the constitution for a 'new Japan'."
Mr Abe said in a statement that he wanted to work "towards a Japan that instils confidence and pride among its children".
His stance is part of efforts to make Japan more assertive on the world stage, with a military able to take part in peacekeeping missions overseas.
The current constitution has already been stretched, allowing the country to have a self-defence force.
Under former Prime Minister Junichiro Koizumi, this was pushed still further, to allow troops to join peacekeeping missions in Iraq.
Critics of the proposed changes say the pacifist constitution has kept Japan out of war since the 1940s, allowing it to avoid the militarism of the early 20th Century and focus on economic growth instead.