The Reuters/Ipsos poll was taken Aug.19-23, the very same week that horrific reports emerged strongly suggesting that Syrian leader Bashar al-Assad has used chemical weapons against his own people, potentially killing hundreds or even thousands of civilians. If there were ever a time that Americans would support some sort of action, you'd think this would be it. But this is the lowest support for intervention since the poll began tracking opinion on the issue. The survey also found that 60 percent oppose intervention outright, with the rest, perhaps sagely, saying that they don't know.
Strangely, 25 percent said that they support intervention if Assad uses chemical weapons. I say strangely because the United States announced way back in June that it believed Assad had done exactly this. A large share of people who answered that the United States should intervene if Assad uses chemical weapons are apparently unaware that this line has already been crossed. Presumably, some number of these people would drop their support if they realized the question was no longer hypothetical.
The United States certainly appears to be considering limited strikes on Syria in response to last week's suspected chemical weapons attack. The calculus for and against is complicated enough in foreign policy terms. But the White House is also a political institution, and it will surely keep the domestic politics, which appear to oppose any intervention very strongly, well in mind.