Broad concern about wider war in the Middle East is dampening public support for U.S. or Israeli military strikes against Iran's nuclear development sites, with Americans by wide margins preferring diplomatic efforts or economic deterrence instead.

Eighty-four percent in this ABC News/Washington Post poll suspect that Iran is trying to develop nuclear weapons, basically unchanged since late 2009. As then, the preferred approaches are direct diplomatic talks between the U.S. and Iran, backed by 81 percent, and an increase in international economic sanctions, supported by three-quarters.

Many fewer, 41 percent, support a U.S. bombing effort, with 53 percent opposed, again similar to 2009. Support for Israeli strikes is virtually identical, with 42 percent in favor and 51 percent opposed. Israel has threatened such strikes; President Obama, while not ruling out military action, has urged allowing more time for sanctions to work, a position criticized by some of his Republican opponents.

RISK OF WAR - Reluctance to support air strikes stems mostly from a broad concern that they could trigger a larger war in the Middle East. Nearly nine out of 10 in this poll, produced for ABC by Langer Research Associates, see a risk of broader war if Israel were to bomb Iran; three-quarters call it a "major" risk.

Among those who perceive a major risk of war, just 32 percent support Israeli strikes against Iranian nuclear sites, and 35 percent back U.S. bombing efforts. Those who perceive little or no risk of sparking a regional war are far more supportive of air strikes - 76 percent support action by Israel, 64 percent by the United States.

WAIT AND SEE? - More than twice as many Americans say it's a better idea to wait and see if economic sanctions against Iran work - even if this allows more time for its nuclear program to progress (64 percent) - than to attack Iran soon, before its nuclear program progresses further than it already has, even if that means not waiting to see if sanctions work (26 percent).

The "wait and see" approach is particularly popular among those who perceive a major risk of wider war. Nearly seven in 10 in this group think the U.S. should pursue sanctions first. Among those who see no risk of war, many fewer, 47 percent, agree.

GROUPS - Preferred approaches to Iran vary as expected by political preference. Fifty-five percent of Republicans support U.S. bombing strikes, compared with 36 percent of Democrats and independents combined. Similarly, support ranges from 55 percent among conservatives to 38 percent of moderates and a quarter of liberals.

Support for U.S. air strikes also is 10 points lower among women than men (36 percent vs. 46 percent); women customarily express lower support for military action. It's also 13 points lower among college graduates than among non-graduates, 32 percent vs. 45 percent.

METHODOLOGY - This ABC News/Washington Post poll was conducted by telephone March 7-10, 2012, among a random national sample of 1,003 adults, including landline and cell-phone-only respondents. Results have a margin of sampling error of 4 points for the full sample. 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.