Chancellor Gordon Brown has renewed his call for a detailed debate on whether MPs should have the final say on sending troops to war.
Mr Brown said liberty was a central British value
In a speech about his personal philosophy, Mr Brown said the limits on government power were an important part of the British tradition of liberty.
There was "a case for detailed consideration of the role of Parliament in the declaration of peace and war".
MPs voted on the Iraq war but the prime minister has power to deploy troops.
Former Cabinet minister Clare Short is trying to push through new laws which would strip the prime minister of his royal prerogative power to take the UK to war.
Under her bill, the prime minister would still be allowed to take urgent action without approval but would be forced to pull the troops back out if Parliament then rejected the move.
Commons leader Geoff Hoon has said the bill could have undesired consequences.
Mr Brown raised the issue during the general election, although Tony Blair said he was merely restating what had happened when MPs were given a vote on the Iraq conflict.
Mr Brown revived the debate on the issue as he gave a lecture at Chatham House, in London, in memory of the late Guardian columnist Hugo Young.
He argued that liberty, responsibility and fairness were together at the heart of "a modern Britishness" and crucial to the country's future success.
Britain was defined not by race, ethnicity or ancient institutions but by shared values, said Mr Brown.
He suggested belief in liberty and placing limits on the power of the executive should be used to continue reform of the House of Lords.
"Our long-held commitment to liberty demands also that we break up any centralised institutions that are too remote and insensitive, devolving and decentralising power...," he argued.
And local councils had to be reinvigorated and local accountability made to work to produce a "new politics".
There must also be new ways of involving people in decisions which affect them, including using "citizens' juries", added Mr Brown.
Such panels of local residents have been used in some areas to show public views on key issues.