In Syria, do Americans hear echoes of Vietnam and Iraq?

Polls consistently show most Americans oppose direct military involvement in the Syrian civil war. But that changes with the presumption that the Assad regime has used chemical weapons.

In deciding to provide weapons to rebels fighting the regime of Syrian President Bashar al-Assad – too late, in the view of many critics – President Obama correctly senses the reluctance of most Americans to engage in foreign wars not clearly tied to national security.

Older Americans remember the sketchy basis for escalating the war in Vietnam (the now-discredited Tonkin Gulf Resolution). Younger people remember the questionable Bush administration argument for the US-led invasion and then occupation of Iraq (those elusive “weapons of mass destruction”).

There are other reasons for Obama’s caution in providing military aid to the Syrian rebels – even light arms and not the heavy weapons they want. For one thing, some of those insurgents have ties to al-Qaeda and other Islamist groups.

Obama feels the political pressure to act now that the “red line” he set – government forces in Syria using chemical weapons against rebels and civilians – has been crossed. Britain, France, and Israel already had already cited the use of chemical weapons. Obama is to meet with Russian President Vladimir Putin this coming week, and Libya surely will be discussed.

Plus, there’s his philosophical and political disinclination to approach what could be a slippery slope. (Remember the talk about “leading from behind” in Libya – a phrase never uttered by Obama but attributed to an advisor?)

So how do Americans feel about this announced escalation of US involvement in Syria – including, according to a Reuters report, consideration of a no-fly zone to limit the regime’s air power.

(Reuters also reports that “Washington has quietly taken steps that would make it easier, moving Patriot surface-to-air missiles, war planes and more than 4,000 troops into Jordan, officially as part of an annual exercise in the past week but making clear that the assets could stay on when the wargames are over.”)

Until now, the pattern in public opinion has been clear.

“Polling conducted in recent months suggests that President Barack Obama is bucking public opinion in opting to authorize military aid to the Syrian rebels,” write Mark Blumenthal and Ariel Edwards-Levy in the Huffington Post.

“Polls have typically shown that as many as two-thirds of Americans oppose military action in Syria, even when questions that specify the aid come in the form of ‘weapons’ rather than more direct military intervention,” they write, citing polls by CBS/NYT, Gallup, NBC/WSJ, Fox News, and HuffPost/YouGov.

For example, Gallup reported two weeks ago that “68 percent of Americans say the United States should not use military action in Syria to attempt to end the civil war there if diplomatic and economic efforts fail, while 24 percent would favor US military involvement.”

A recent NBC News/Wall Street Journal survey had just 15 percent of respondents favoring “military action to help stop the killing,” and even fewer (11 percent) agreeing that the US should “provide arms to the opposition.”

“The hesitation for US involvement in Syria closely matches twenty-five years of past data showing the reluctance Americans have about intervening between two conflicting factions within a foreign country, especially when there is no perceived threat to US national security,” writes Paul Donaldson of Public Opinion Strategies, a national Republican political and public affairs research firm. “Looking at other civil-wars/foreign conflicts, we see similar opposition to sending in our military.”

Is the Syrian regime’s “red line” use of nerve gas changing attitudes? Perhaps.

An April Pew Research survey found plurality support (45 to 31 percent) for military action, "if it is confirmed that the Syrian government has used chemical weapons against anti-government groups," the HuffPost writers note. Similarly, a CNN/ORC survey in May found 68 percent thought military action justified "if the United States were able to present evidence that convinced you that the Syrian government has chemical weapons and has used them to kill civilians in that country."

Whether or not evidence of the use of nerve gas in Syria is “convincing” is an open question.

Writing on the New York Times FiveThirtyEight polling aggregation web site, Micah Cohen finds that when questions about US military involvement in Syria include the presumption that the Assad regime used chemical weapons, “support for intervention increased substantially.”

“According to an average of the three surveys in the PollingReport.com database that asked, 58 percent of adults said they would support military intervention if it were confirmed that the Assad regime had used chemical weapons either on antigovernment forces or on civilians,” Mr. Cohen writes.

That’s the tenuous political ground on which Obama stands as he decides the next US steps on Syria.