Obama won't rush to act against Syria over chemical arms By Steve Holland and Warren Strobel WASHINGTON (Reuters) - President Barack Obama signaled on Tuesday that he is no rush to respond quickly to Syria's apparent use of chemical weapons, taking a cautious approach to the Arab country's civil war that mirrors the views of the U.S. public, most lawmakers and some American allies. Obama, who last year declared that the use or deployment of chemical weapons by Syrian President Bashar al-Assad would cross a "red line," told a White House news conference there is evidence those weapons were used, but that there is still much U.S. intelligence agencies do not know. "We don't know how they were used, when they were used, who used them," he said, and, "We don't have a chain of custody that establishes what exactly happened." Obama did not rule out action - military or otherwise - against Assad's government. But he repeatedly stressed he would not allow himself to be pressured prematurely into deeper intervention in Syria's two-year-long civil war. The president's remarks raised the prospect that, despite declaring last week that there is evidence Assad has used the nerve agent sarin "on a small scale," any U.S. government response will not be quick. Obama's press secretary Jay Carney told reporters on Monday that there is no deadline for rendering a final judgment on whether chemical weapons were used, and by whom. "I would not give you a timetable," Carney said. Privately, U.S. officials predict it will be weeks before any conclusion is reached. Syria denies using chemical weapons. Obama administration officials have not specified what "physiological" evidence they have that Syrian forces used sarin, but government sources said it includes samples of blood from alleged victims, and of soil. The evidence is "fragmentary" at best, but appears to indicate the use of sarin on two occasions, said a European national security official who spoke on condition of anonymity. Since the Syrian conflict erupted in 2011 - it has killed 70,000 people and created more than 1.2 million refugees - Obama has repeatedly shied away from deep U.S. involvement. That stance is shared by top Pentagon officials, who have spoken publicly and privately of their concerns about the limits and risks of employing U.S. military force in the shattered country. Whether Obama is now slowly moving toward a more activist approach is unclear. He faces criticism for softening a "red line" that seemed crystal clear when he said in August that the use of chemical weapons by Assad, or transfer of stockpiles to extremist groups would be unacceptable. White House officials said they do not think the U.S. public is eager to get involved militarily in Syria. "Setting aside instances when America has been attacked - the Japanese and al Qaeda - military action should always be something any president considers very seriously and deliberately and that's especially the case when it's not an attack on the United States," a senior White House official said. A New York Times/CBS News poll released on Tuesday found that 62 percent of Americans say the United States has no responsibility to do something about the fighting between Assad's forces and anti-government rebels. Only 39 percent of respondents said they were following the Syrian violence closely, indicating it is not among U.S. citizens' top concerns. I think the American people are kind of where the president is. You've got to have some definitive evidence and you've got to very careful about what you do," said Democratic strategist Bob Shrum, who managed John Kerry's 2004 presidential campaign. The politics of this is not hard for the president. It's the policy that's hard," Shrum said. Obama also has room for maneuver on Syria because Republican are divided over what to do, and - unlike with Iran's nuclear program - close U.S. Middle East ally Israel is not urging American action. Some prominent Republicans, including senators John McCain of Arizona and Lindsey Graham of South Carolina, cited the chemical weapons evidence to renew their calls for action such as establishing a no-fly zone to neutralize Syria's air defenses. But not all Republicans share that view. Departing from his party's frequent disparagement of the United Nations, Representative Harold Rogers of Kentucky replied when asked if Washington should arm the Syrian rebels: "It is such a muddled picture. I think probably we ought to be asking the U.N. to be involved. The Republican divide "leads to an incoherent critique of the administration's policy," said Jon Alterman, director of the Middle East program at the Center for Strategic and International Studies think tank. There is also "the long hang-over from Iraq" and the U.S. war there, Alterman said. I don't know when that goes away. Michael Oren, Israel's ambassador to the United States, said his country is not calling on Obama to act against Syria. "We're not making any policy recommendations," Oren said in a telephone interview. We think the issue is very complex. At his news conference, Obama insisted that "I've got to make sure I've got the facts" before declaring that the red line was crossed. "If we end up rushing to judgment without hard, effective evidence, then we can find ourselves in the position where we can't mobilize the international community to support what we do," he said. Said Alterman: "Obama is looking for an opportunity to be decisive" in Syria. You could either see it as reluctance, or patience. Additional reporting by Patricia Zengerle, Mark Hosenball and Tabassum Zakaria; Editing by Alistair Bell and Mohammad Zargham