As an initial wave of outrage over a chemical weapons attack in Syria subsides and planning for a military response proceeds, Western nations are increasingly gripped by doubt.
Politicians and the international public alike were shocked by news of a chemical strike on civilians in a Damascus suburb, but support for a punitive strike is not universal.
The recent experience of brutal wars in Iraq and Afghanistan has left many leaders and voters gun shy, and US President Barack Obama has a tough task selling the idea of allied action.
In London, Prime Minister David Cameron was among the first to blame Syrian President Bashar al-Assad's regime for the gas attack, which reportedly killed more than 350 people.
But now he faces a parliamentary revolt as he seeks backing for British participation in allied counter strikes, which the opposition Labour Party and many in his own camp oppose.
A Labour source said the party has "increasing doubts" about Cameron's motion, which "does not mention anything about compelling evidence" that the attack was launched by Assad's troops.
The British public -- wary of getting bogged down in a drawn out war like the one in Iraq, which was based in part on faulty intelligence -- has soured on a possible attack.
A YouGov poll found that support for firing British missiles against Syria had dropped to 22 percent by Wednesday, while opposition rose to 51 percent.
A British draft resolution backing action against Syria went nowhere Wednesday in the UN Security Council, where Russia -- which has supported Damascus throughout the 29-month Syrian conflict -- blocked the effort.
Obama said his administration has concluded that Assad's regime was behind last week's attack, but other countries have taken a pause as they await the report by UN investigators.
In Germany, 58 percent of respondents to a ZDF television poll said they remain opposed to military intervention, with 33 percent saying Western powers should strike Syria.
France, the United States and Britain have spearheaded calls for military action, but the French public is split, according to two polls which put support for a intervention -- even one with UN backing -- at only 55 or 45 percent.
Italy, which served as a launchpad for strikes against Libya in 2011, has taken a backseat, ruling out participation in any military intervention in Syria without a Security Council mandate.
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In Austria and Spain, politicians and the press urged caution and stressed that no action should be taken before UN inspectors present their evidence.
"The United States must consider the consequences of a response to Syrian provocation," Spain's El Pais newspaper said in an editorial.
"War should always be a last resort."
Even Poland, a staunch US ally and major contributor of troops for the US-led wars in Iraq and Afghanistan, appears opposed to forceful intervention.
"I'm not convinced that an armed attack will stop the crimes," Prime Minister Donald Tusk said Wednesday.
Across the Atlantic the potential for conflict has dominated media coverage, with The New York Times and Washington Post both warning that Obama has yet to make a convincing case for action against Syria.
Many on Capitol Hill thumb their nose at the United Nations and would not hesitate to act without Security Council approval.
But House Speaker John Boehner nevertheless suggested Obama has not done enough to justify intervention.
"What is the intended effect of the potential military strikes?" Boehner asked Obama in a letter.
With Iraq or Afghanistan no doubt in mind, many lawmakers are urging Obama to make his case and gain congressional approval before launching an attack.
Democratic Senator Chris Murphy came out forcefully against a military strike.
Such an attack, he told NBC, may make those appalled by chemical weapons "feel better, but it may not actually make the Syrian people safer or advance US national security interests.
"If you drop a bunch of bombs on Syria today and don't remove Assad from power, you potentially make the situation worse for the Syrian people and you potentially drag us into a conflict that could last a decade."
Key US ally Canada, meanwhile, announced Thursday it would support Western military intervention but would not participate.