LONDON - Prime Minister David Cameron may have won an unexpectedly decisive election victory in May, but he has yet to convince Britain's allies he is a globally engaged foreign policy player.
Washington watched with alarm as Cameron presided over a downgrading of Britain's military and diplomatic muscle during his first term, culminating two years ago with his loss of a crunch parliamentary vote to authorize air strikes on Syria.
"Our concern is a great shrinking Britain," one senior U.S. diplomat bemoaned recently.
Stung by such talk, Cameron is banking he can now convince his country's parliament to vote to join U.S.-led air strikes on Islamic State militants in Syria.
He calculates such a move — not expected until after the summer — should re-establish his international statesman credentials.
After fighting an unusually parochial election campaign, he has begun to talk up his foreign policy ambitions, declaring at a summit of world powers in Germany last month that Britain was "back."
He then pledged to keep defense spending at NATO's target of 2 percent of gross domestic product, a policy he had initially resisted committing to because of his desire to cut Britain's sizeable budget deficit.
The memory of his humiliating 2013 parliamentary defeat over taking military action against Syrian government forces — seen internationally as a sign Britain was retreating from the world — still rankles though.
"The damage it did was far and away greater than any of us expected, and it has hung on this leadership... he is trying to distance himself from that embarrassment," Michael Clarke, Director General of defense and security think tank the Royal United Services Institute, told Reuters.
Clarke said the fact Cameron narrowly avoided presiding over the break-up of the United Kingdom at last year's Scottish independence referendum, and his demands for changes to Britain's ties with the European Union ahead of a membership vote, had also damaged his standing.
"His international reputation isn't that high... so he has got quite a lot of bouncing back to try to do," said Clarke, adding that Cameron's pledge not to seek a third term means he now has an eye on his legacy.
"He wants to personally restore his image as a world leader of some importance, not [be seen as] the coalition prime minister who presided over a retreat on all fronts.
The political situation has changed since parliament's 2013 vote on Syria. Back then, Cameron was seeking approval to target Syrian government forces in retaliation for their suspected use of chemical weapons. U.S. President Barack Obama eventually called off the strikes after Syria promised to give up its chemical arsenal.
This time, the target is Islamic State, the militant group that has seized swaths of Iraq and Syria, beheaded British hostages and whose followers claimed responsibility for a Tunisia attack in June in which 30 British holidaymakers were killed. The government says it poses a direct threat to Britain.
The United States has been leading a coalition of Western and Arab countries bombing Islamic State positions in both Iraq and Syria since last year. Britain has sent jets to participate in the bombing raids in Iraq, but not in Syria.
The limited role is a big change from Britain's position as Washington's main battlefield ally under Cameron's predecessors Tony Blair and Gordon Brown, when tens of thousands of British troops served in Afghanistan and Iraq and more than 600 died.
That heavy cost has made the British public reluctant to back new military action. But a YouGov poll this month found 57 percent of Britons would back the Royal Air Force joining strikes in Syria, compared to 21 percent who were opposed.
Scarred by the events of 2013 when he recalled parliament during the summer break for a rushed and ultimately unsuccessful vote, Cameron is taking a more cautious approach at building support this time.
Earlier this month, he invited senior opposition Labor Party lawmakers to a national security meeting to be briefed on the IS threat. He is not expected to push for a vote until after Labor has elected a new leader on September 12.
"If we lost the vote again it would be game over for Britain. The prime minister won't do it unless he is sure he can win," said a senior government aide, describing Labor as "skeptical but persuadable".
Good will among lawmakers was dented last week however when the Ministry of Defense disclosed that British pilots embedded with U.S. and Canadian forces had already taken part in air strikes in Syria without lawmakers' knowledge.
That prompted some politicians to complain that the will of parliament had been ignored. Several lawmakers on Monday said the government would need to do more to persuade them of the merits of Britain extending military action to Syria.
"You can't take parliament with you if you keep parliament in the dark," said Labor defense spokesman Vernon Coaker.
Defense Secretary Michael Fallon, who said it was illogical to target IS in Iraq but not Syria, said the high precision missiles Britain's Tornado aircraft fire was one of the reasons its allies were keen for it to join the action in Syria.
Yet while bombing Syria may go some way towards resurrecting Britain's global clout, U.S.-led forces are hardly short of firepower, and the addition of British aircraft is not likely to make a major difference to the mission.
Critics say gains by Islamic State in both Iraq and Syria show the limits of the U.S.-led strategy of bombing from the air, and that Western ground forces may be needed.
Cameron and Fallon have repeatedly said there is no question of British "boots on the ground".
But David Richards, former chief of Britain's defense staff and commander of international troops in Afghanistan, said the issue of British ground troops would need to be revisited if no progress was made in the next year.
"The current strategy is essentially one of equipping and training others to do the hard stuff for us. I think that could work, but the scale of effort going into it is woefully insufficient," Richards told the BBC's Andrew Marr show.
"If you really want to get rid of them, we need to effectively get on a war footing."