Ingram also insisted that general Sir Richard Dannatt, the army chief, had not gone too far by calling for British troops to withdraw from Iraq "sometime soon".
Ingram, speaking at RAF Molesworth air base in eastern England on Monday, said: "We do need a national debate about what we are doing in Iraq and Afghanistan and the Balkans and elsewhere."
And he backed Dannatt, who warned on Friday that withdrawal was needed soon from Iraq because the presence of British troops at times exacerbated Britain's security problems there and around the world..
He said: "It is only right and proper that there is an open and mature national debate rather than a media feeding frenzy in which people's comments can be taken out of context.
"I don't think he [Dannatt] overstepped the mark. That is the job of senior military commanders. They have got to tell the truth. They cannot hide the truth.
"He was not saying anything much different from our own views."
Dannatt's comments last week in an interview with the Daily Mail newspaper provoked a furore in Britain.
He was widely interpreted as contradicting the defence of Tony Blair, the prime minister, of the presence of British troops in Iraq in September, when he said that if Britain were to withdraw, the country "will be committing a craven act of surrender that will put our future security in the deepest peril".
Dannatt later said British troops would remain in Iraq "until the job is done" and said their withdrawal should not be linked to any problems over their presence there.
He later received Blair's backing.