Obama treads lightly amid chemical attack allegations in Syria WASHINGTON - Facing mounting pressure to respond to new reports of brutality by the Syrian government, President Obama on Friday downplayed the likelihood of a U.S. military intervention and dismissed as overstated the notion that the United States alone could end Syria's raging civil war. European leaders condemned the alleged poison gas attack that apparently killed more than 100 people near Damascus this week. Even Russia, a key ally of Syrian President Bashar Assad, joined those calling on his government to allow United Nations inspectors already in Syria to try to determine what happened Wednesday. In his first comments about the attack, which produced more disturbing images Friday of Syrian children wrapped in white burial shrouds, Obama carefully avoided saying Assad had crossed the "red line" that the president set last summer as a trigger for possible U.S. intercession. Use of chemical weapons, he said at the time, would "change my calculus." Appearing on CNN, Obama called reports of a chemical assault "troublesome" and "a big event of grave concern" that has hastened his time frame for a possible response. "This is something that is going to require America's attention," he said. Obama, who entered the White House vowing to end America's wars in Iraq and Afghanistan, warned of getting "drawn into very expensive, difficult, costly interventions that actually breed more resentment in the region." "If the U.S. goes in and attacks another country without a U.N. mandate and without clear evidence that can be presented, then there are questions in terms of whether international law supports it," Obama said. Do we have the coalition to make it work? Those are considerations that we have to take into account. Obama's reluctance to intervene got a tacit vote of approval when he appeared at a town hall meeting at Binghamton University in upstate New York. In an hourlong, free-ranging question-and-answer period, not one person asked about his plans for Syria or expressed concern about events there. For much of the summer, the more than two-year-long civil war in Syria has been overshadowed in Washington by the crisis in Egypt, where the military ousted a freely elected leader and shot and killed hundreds of Islamist protesters who had rallied in his support. The gruesome images from Syria this week put the calamity there back in the forefront. It also has exposed a clear division in the White House about any possible response. Some of Obama's top aides are counseling caution, warning that Syria's treacherous political landscape could ensnare U.S. forces, just as Iraq did. But other senior aides have pressed the president to consider more forceful action, arguing that America must respond to the use of chemical weapons, which are barred by international treaty, if proof is obtained that Assad's forces launched such an attack. Top national security advisors at the White House confirmed they were updating a possible target list for airstrikes if Obama decides to order a military response. Officials said they are not considering sending U.S. troops to Syria, or creating a "no fly zone" by sending U.S. warplanes to eliminate Syrian air defenses and aircraft to protect civilians, as was done in Libya in 2011. Other possible options include cruise missile strikes or a more sustained air assault. Missiles could be launched from warships in the Mediterranean, and bombers and other aircraft deployed in the Middle East could be redirected to Syria. After months of delays, a 20-member U.N. team arrived in Damascus on Sunday with a limited mandate to investigate allegations of three chemical attacks that occurred months ago. There was no word Friday whether the Syrian government would allow the team to collect evidence from the latest incident. The U.N. high representative for disarmament affairs, Angela Kane, was expected to arrive in Damascus on Saturday in a bid to push for access to the sites of the alleged attacks. The opposition charges that military forces unleashed poison-gas-tipped rockets on rebel strongholds to the east and south of the capital. Syrian authorities have vehemently denied the allegations. Video and photographs said to show victims, including many women and children, have caused worldwide revulsion. Experts have said the images are inconclusive but may indicate that a nerve agent was deployed. News agencies reported Friday that U.N. Secretary-General Ban Ki-moon had said the use of chemical weapons in Syria would "constitute a crime against humanity." There was "no time to lose" in getting to the bottom of the matter, he said during a visit to Seoul. Although Russia called for further investigation, authorities in Moscow suggested it was Syrian rebels, not Assad's military, who carried out the attack in a bid to discredit the government and spur international intervention. "We are dealing with a preplanned provocation," Foreign Ministry spokesman Alexander Lukashevich said in Moscow. But Britain, a major supporter of the Syrian opposition, said Assad's government probably was the culprit.