President Barack Obama said on Friday that Syria’s civil war “is going to require America’s attention and hopefully the entire international community’s attention,” days after opposition activists in the country accused the regime of President Bashar Assad of gassing hundreds of civilians in a suburb of the capital Damascus.

“That does not mean that we have to get involved with everything immediately,” the American leader cautioned during an interview for CNN’s New Day television program.

Public support for military intervention is limited. Few Americans favor deploying soldiers to a third country in the Middle East after more than a decade of wars in Afghanistan and Iraq.

Obama also warned that the United States might not be able to solve “what is a sectarian, complex problem inside Syria.”

However, the alleged use of chemical weapons, he said, “starts getting to some core national interests that the United States has, both in terms of us making sure that weapons of mass destruction are not proliferating, as well as needing to protect our allies, our bases in the region.” As for intervention, “We have to think through strategically what’s going to be in our long-term national interests.”

A year ago, the president warned the Assad regime that it would cross a “red line” if it used chemical weapons. “That would change my calculus,” Obama said at the time.

As was the case when chemical weapons were allegedly used earlier this year, Reuters reports that American intelligence has not been able to determine conclusively that a chemical agent was deployed this week. In April, officials said they believed with “varying degrees of confidence” that sarin had been used by Assad’s army. However, they noted that “the chain of custody is not clear,” suggesting that an order to deploy the nerve gas might not have come from the top.

There is also the possibility that gas was used by rebels emboldened by the American president’s promise of more aid if chemical agents were deployed. The incident in April prompted his administration to announce that it would provide rebel fighter with small arms — although The Washington Post reported at the time that the decision to send weapons into Syria was actually made weeks in advance when support from Hezbollah militiamen from neighboring Lebanon seemed to turn the war in Assad’s favor.

The United States were previously reluctant to arm rebels for fear of propping up a jihadist insurgency. Most of the communications equipment and weapons supplied by the United States and its allies in the region, including Qatar, Saudi Arabia and Turkey, ended up in the hands of religious extremists who still appear to be the most effective fighting force in the opposition.