According to Hillary Clinton, David Cameron's historic parliamentary defeat, in which MPs voted against the government's proposed use of British military forces against Syria in August last year, exerted some influence over the US decision to likewise pull back from strikes against the Assad regime.
Both countries, scarred by the experience of Iraq, were unable to countenance another intervention, even, as was the case in Syria, with the regime deploying chemical weapons against its detractors. Of course, domestic politics played a role both in London and Washington, however for the two nations that led the charge against Saddam in 2003, intervention, it seemed, was now off the table.
A year later and the black flags of the Islamic State (formerly ISIS), currently fluttering across lands from from northern Syria to the Iraqi province of Diyala north-east of Baghdad, have once again pushed the noxious issue of intervention to the forefront of the US foreign policy debate - a discourse that is further dividing an already fractured Republican Party, with the question of action versus non-action likely to run all the way to the 2016 election.
In recent weeks, Bush-era Republicans have been sought for comment on the arrival of "Caliph" al-Baghdadi, most notably Dick Cheney, the ageing hawk revelling in the unexpected limelight and his chance to peddle aged bluster about long-discredited "links" between Saddam and al-Qaeda.
Yet Cheney's Punch and Judy sideshow (the former VP is routinely hit over the head by everyone from his own party to Fox News) was just a foretaste to a more bitter debate that finally blossomed this week, with the crisis in Mesopotamia pitting traditional interventionist Republicans against the party's youthful Libertarian and isolationist flank.
The debate was mediated through rival newspaper columns penned by Kentucky Senator Rand Paul and Governor Rick Perry of Texas - both already limbering up for a tilt at the Republican presidential nomination and the chance to thwart the other Clinton from entering the White House 15 years after the last one left.
Writing in the Washington Post, Perry outlined a worldview in which American security is best served through muscular interventionism, a traditional perspective not far removed from the last Bush White House and indeed most Republican administrations dating back to the Sixties. In his article, the Governor attempted to paint Paul as an isolationist, a timid idealist who would prefer "accommodation" with those that would threaten the homeland rather than revert to the use of force.
On Iraq and Syria, Perry wrote that the Islamic State was a "real threat to our national security - to which Paul seems curiously blind - because any of these passport carriers can simply buy a plane ticket and show up in the United States without even a visa." He continued: "It's particularly chilling when you consider that one American has already carried out a suicide bombing and a terrorist-trained European allegedly killed four at the Jewish Museum in Brussels. Yet Paul still advocates inaction."
Paul responded by allying Perry to Cheney and Bush - a member of the "let's intervene and consider the consequences later crowd" - hawks that would honour American troops already lost in Iraq by sending in several thousand more to likely meet the same end.
Writing in Politico, Paul retorted: "I ask Governor Perry: How many Americans should send their sons or daughters to die for a foreign country -- a nation the Iraqis won't defend for themselves? How many Texan mothers and fathers will Gov. Perry ask to send their children to fight in Iraq? I will not hold my breath for an answer. If refusing to send Americans to die for a country that refuses to defend itself makes one an "isolationist," then perhaps it's time we finally retire that pejorative."
Although Paul's is the minority view within the Party, a recent poll showed that 52% of Republicans said that the US military did "too much" overseas, while the same overall percentage wanted the US to "mind its own business internationally and pay more attention to problems at home". According to Pew, this is the highest measure of international disengagement in more than half a century, while support for US engagement overseas is currently close to an historic low. If the US is changing, it is going in the direction of the Senator from Kentucky.
Still, the historical pull for the US to try and reshape the world aboard to better serve its interests at home will be a difficult orbit from which to break, particularly as many of the same justifications for intervention - to enhance US credibility abroad and to provide reassurance to allies in the region - remain potent, particularly to those on the right.
The effectiveness of Paul being able to counter those traditional arguments will likely go a long way to shaping not only the next election but perhaps even America's future role in the world.