While Americans broadly prefer to stay out of direct involvement in the conflict in Syria, support for U.S. military action soars in the event of a loss of control of its chemical weapons, the use of such weapons on the Syrian people or an attack on neighboring U.S. allies.

Most in the latest ABC News/Washington Post poll also say they'd support the imposition of a no-fly zone over Syria, provided U.S. ground forces are not involved.

See PDF with full results and charts here.

In general, 73 percent say the U.S. military should not get involved in the conflict. But almost exactly as many say they'd support U.S. military involvement if Syria were to lose control of its chemical weapons, as do 63 percent if the Assad regime used these banned weapons against its own people - an action that Barack Obama has warned would "cross a red line."

Similarly, if Syrian forces were to attack nearby U.S. allies, 69 percent say they'd support U.S. military involvement. And regardless of any such specific provocation, 62 percent say they'd favor creation of a no-fly zone, provided no ground troops were used. (That may reflect the success of the no-fly zone over Libya, general preference for air vs. ground combat, or some combination of both.)

Even among those who initially oppose U.S. military intervention, more than half change their position given the specific circumstances proposed, including 69 percent who, despite initial hesitancy, support U.S. involvement if Syria's chemical weapons stockpile became insecure.

More generally, this poll, produced for ABC News by Langer Research Associates, finds the American public wary of the unrest in Syria and the course of the Arab Spring more broadly. Majorities think these events will harm, not help, U.S. political and economic interests in the region, and more think they'll harm rather than help U.S. efforts to fight terrorist groups.

Fewer than a quarter think the outcome of the Syrian and broader Middle East/North Africa unrest will ultimately help U.S. political and economic interests. And Americans by 44-26 percent think the events in Syria will harm the United States' ability to fight terrorist groups in the region. The public by 52-28 percent says the same about the Arab Spring more generally.

GROUPS - Initial reluctance to involve the U.S. military in Syria is broadly based, with, for example, roughly equal numbers of Democrats, Republicans and independents opposed. Opposition rises with age, from 66 percent of 18- to 29-year-olds to eight in 10 seniors.

Partisan differences emerge in some of the specific scenarios. Support for U.S. involvement is 13 points higher among Republicans than independents (with Democrats in the middle) if Syria loses control of its chemical weapons stockpile, 12 points higher among Republicans and independents than among Democrats if chemical weapons are used on the Syrian people, and 10 points higher among Republicans than Democrats and independents if U.S. allies are attacked.

There's no such gap on a no-fly zone, supported by 67 percent of Republicans, 62 percent of independents and 60 percent of Democrats alike.

OBAMA - More oppose than support Obama's decision to recognize the Syrian rebel groups as the country's legitimate government, 47 to 29 percent, though nearly a quarter have no opinion on the move. (Criticism peaks among Republicans and conservatives.) Support for military intervention rises among those who support Obama's recognition of the Syrian opposition, vs. those who oppose it.

Obama more generally has a 54 percent approval rating for handling international affairs, its highest in three years, matching his post-election job approval rating overall.

METHODOLOGY - This ABC News/Washington Post poll was conducted by telephone Dec. 13-16, 2012, among a random national sample of 1,002 adults, including landline and cell-phone-only respondents. Results have a margin of sampling error of 3.5 points, including design effect. Partisan divisions are 31-24-38 percent, Democrats-Republicans-independents.

The survey was produced for ABC News by Langer Research Associates of New York, N.Y., with sampling, data collection and tabulation by Abt-SRBI of New York, N.Y.