President Barack Obama and British Prime Minister David Cameron hold a joint press conference during the G7 Summit at the European Council in Brussels in June. (Saul Loeb/AFP/Getty Images)

LONDON — When the British House of Commons voted last summer to buck calls to join the United States in a possible military intervention in Syria, it set off a furious round of soul-searching over whether the unbreakable bond between London and Washington had just sustained a grievous blow.

The ever-provocative Sun even ran a front-page death notice marking the passing of the Special Relationship, “beloved offspring of Winston Churchill and Franklin D. Roosevelt,” at age 67.

Tabloid hyperbole aside, the concerns have been real for some time. The most recent American-British military ventures – Afghanistan, Iraq, Libya – haven’t gone so well. During the height of the global financial crisis, it was Berlin, not London, that officials in Washington kept on speed dial. Meantime, Britain’s clout within Europe has diminished, with legitimate questions about whether London has the ability or the will to sway the continent to Washington’s liking.

The doubts have taken on a greater urgency in recent months, ever since Russian President Vladimir Putin began dismembering Ukraine. Faced with the greatest security challenge in Europe since the end of the Cold War, the United States took a relatively hard line, and enacted a spiral of ever-tougher sanctions.

Europe wavered, and for a time, it looked as though Britain was joining right in with the less-than-forceful response. A top British security official was photographed this spring with the diplomatic equivalent of his pants around his ankles: He was carrying, for all the world to see, a briefing paper that suggested Britain would put the interests of its go-go financial sector ahead of punitive measures that might restrain Putin.

But that changed with this month’s downing of Malaysia Airlines Flight 17 over eastern Ukraine. Within days, British Prime Minister David Cameron was on the floor of the House of Commons, trying to cajole, and shame, his European colleagues into joining the United States in ensuring Russia didn’t get off lightly for its apparent role in the plane’s destruction.

Cameron didn’t shy from naming names: A French deal to send warships to Russia, he noted, would be “unthinkable” in the United Kingdom.

The comments drew charges of hypocrisy from Paris, where French politicians pointed out that London has long been a cozy second home for Putin’s favorite oligarchs. But in the end, Cameron’s prodding may have helped move his counterparts toward a deal that allowed the United States and Europe to announce on Tuesday a series of coordinated measures targeting the Russian defense, finance and energy sectors.

In a stroke, the package eliminated the substantial daylight that had grown between the United States and Europe – and reminded Washington what makes its relationship with London so special.

Britain’s renewed role as American wing-man in Europe was on display again Thursday with the release of a parliamentary report that declared NATO to be unprepared for the Russian threat.

The report, released by the Commons Defense Committee, calls for Europe to wake up to the challenge of a revanchist Russia after decades of slumber, and recommends a beefed up presence in vulnerable Baltic states. It also urges Europe to pump money back into its under-funded militaries, which have withered amid the continent’s economic decline.

Washington has long made the same plea, but the report will help ensure the issue sits high on the agenda when NATO leaders gather for the organization’s biennial summit in early September -- an event that, for the first time since the Cold War’s end, will be hosted by Britain.