NEWPORT, Wales - President Obama came here to shore up NATO support for intervention against the Islamic State and enlisted an ally who has also endured criticism and setbacks over the issue - British Prime Minister David Cameron.

The summit on Cameron's home turf allowed the men to reaffirm the partnership between the U.S. and its closest ally. It also allowed the two men, who are not as personally close and on opposite sides of the political spectrum as previous presidents and prime ministers, to strengthen their personal relationship.

But the two men were able to show their united front on one issue: the Islamic State.

Obama and Cameron penned an op-ed in the Times of London Thursday, where the two men rejected calls for an "isolationist approach" and asked fellow leaders to "summon up the shared resolve that inspired NATO's founding fathers."

It was a show of solidarity on the Islamic State that has taken time to gel. When Obama announced targeted air strikes against the Islamic State last month, Britain - which almost always partners with the U.S. on military interventions, did not participate.

The specter of the Islamic State is something that has been consuming both men this summer.

Both men were chided for going on vacation -- Obama to Martha's Vineyard, Cameron to the British seaside resort of Cornwall -- as news of the Islamic State intensified.

“Wherever I am in the world I am always within a few feet of a BlackBerry, and an ability to manage things should they need to be managed,”
Cameron said. The White House had also gone to great lengths to display that President Obama does, in fact, work quite a bit on vacation, traveling with a massive entourage of staff and communications equipment and putting out numerous readouts of calls he made to world leaders on his break.

But the two men took different approaches to the death of James Foley, an American journalist who was beheaded by a militant with a British accent. Obama was chided as weak and out of touch when he went golfing four minutes after delivering a solemn statement on Foley's death.

Cameron, on the other hand, cut short his vacation in the seaside resort of Cornwall and rushed back to 10 Downing Street after it became apparent that a British citizen may have beheaded Foley. The British government confirmed they believe a British national killed the journalist.

Now the specter of Syria looms large a year after Cameron suffered a stinging defeat when the House of Commons defeated his proposal to take military action against Syria after President Bashar al-Assad used chemical weapons in an attack. Obama made the case for military action but did not take it because there was little support from Congress.

This year, however, the threat of foreign fighters holding Western passports has placed the issue squarely on the table again.

A senior administration official said there was unanimous consensus among the NATO allies that in order to, as President Obama said, “degrade and destroy” the Islamic State some action will likely be required in Syria. However, the alliance is taking "first things first" and focusing on fighting the group in Iraq, where it is on the move.

European countries feel threatened because some of the Islamic State’s members hold Western passports.

“We heard a lot about that in the closed sessions,” from Europeans, this person said. “These government leaders, that really has their attention.”

Deputy National Security Adviser Ben Rhodes said it is up to Cameron to decide if the United Kingdom will participate in air strikes, but that is a "unique nature" to the situation of the Islamic State because of foreign fighters.

"There’s no country that we are more in sync with in terms of our values and our foreign policy and our security cooperation around the world than the United Kingdom. And I think that is the spirit that illuminates the discussion that the president had with the prime minister," Rhodes said.