DAMASCUS, Syria – Syria on Sunday derided President Obama’s decision to hold off on punitive military strikes, but also took precautions by reportedly moving some troops and military equipment to civilian areas.

The Obama administration countered that its case for military action against the regime of Syrian President Bashar Assad is getting stronger, saying it now has evidence that the toxic gas allegedly used in strikes on rebel-held areas was the nerve agent sarin.

The administration predicted Sunday it will obtain congressional backing for limited strikes. After days of edging closer to military action against Syria, Obama suddenly announced Saturday he would first seek approval from Congress, which gets back from summer break Sept. 9.

Assad, in turn, tried to project confidence in his escalating showdown with the U.S., saying in comments carried by state media Sunday that Syria is “capable of confronting any external aggression.”

From the sidelines, others exhorted the U.S. either to get involved or stay out of the brutal 2½-year-old conflict that has claimed more than 100,000 lives and displaced millions of people.

The Arab League at an emergency meeting in Cairo Sunday called on the United Nations and the international community to take “deterrent” measures under international law to stop the Syrian regime’s crimes, but could not agree on whether to back U.S. military action.

Arab foreign ministers at the meeting in their closing statement held the Assad regime responsible for the “heinous” chemical attack, saying the perpetrators should be tried before an international court “like other war criminals.”

Syria’s deputy foreign minister, Faysal Mikdad, claimed Sunday that Obama stepped back from his threat to attack because he lacks evidence of Syrian government involvement in the Aug. 21 attacks.

“The hesitation and the disappointment is so obvious in the words of President Obama yesterday,” Mikdad told reporters in Damascus. “The confusion was clear as well.”

In Washington, U.S. Secretary of State John Kerry tried to sharpen the arguments for military action Sunday in a serious of appearances on television news shows.

Kerry said he expected American lawmakers to recognize that the “credibility of the United States is on the line.”

He said Obama has the authority to launch retaliatory strikes with or without Congress’ approval, but Kerry stopped short of saying the president would do so if the House or Senate withholds support.

“The stakes are just really too high here,” Kerry said. “We are not going to lose this vote.”

Kerry also said the United States has received hair and blood samples from first responders indicating that Syria’s government forces used sarin in the Aug. 21 attacks. It was the first piece of specific physiological evidence cited by the administration.