President Obama has not yet decided on U.S. action in Syria, where he says his administration has "concluded" President Bashar al Assad used chemical weapons in an attack against civilians last week near Damascus.
"I have gotten options with our military, had extensive conversations with my national security team," the president said Wednesday in an interview with "PBS NewsHour." "If the Assad regime used chemical weapons on his own people, then that would change some of our calculations - and the reason has to do with not only international norms but America's own self-interest."
Employing his sharpest language to date as to who - Assad or the rebels fighting him - was responsible for the Aug. 21 strike in the civil war-torn country, Mr. Obama defined Vice President Joe Biden's assessment Tuesday that there is "no doubt" the Syrian government was at fault: "We have concluded," the president said, that Assad's regime "in fact carried these out. And if that's so, there needs to be international consequences.
"...We have looked at all the evidence and we don't believe the opposition possessed... chemical weapons of that sort," he continued. "We do not believe given the delivery system using rockets, that the opposition could have carried out these attacks."
While he's engaged in talks with U.S. allies and the international community as a whole, the president said, he assured he has "no interest in any open-ended conflict in Syria." But, he added, "we do have to make sure that when countries break international norms on weapons like chemical weapons that could threaten us, that they are held accountable. ...We cannot see a breach of the non-proliferation norm that allows potentially chemical weapons to fall into the hands of all kinds of folks."
Members of the administration have said they will soon release an unclassified intelligence report laying out the details of what they believe transpired in Syria. However, the White House said Wednesday that the the report is not finished and that the intelligence community is "still working it."
Senior officials concede the timing of a possible military strike is complicated by next week's G-20 Summit in Russia.
While it is possible to launch an attack during a high-profile global economic summit of that kind, it is highly unlikely, due to the diplomatic issues it may raise with Russia, a country the U.S. already has frosty relations with.
"I doubt it," said another administration official involved in the Syria strategy discussions about a strike during the summit.
The potential for a military strike in Syria has triggered some concern on Capitol Hill, where lawmakers are pointing out that the president cannot legally use military force without congressional approval. As of Wednesday afternoon, 116 lawmakers had signed onto a letter calling on the president to get Congress' authorization before acting militarily.
Earlier Wednesday, House Speaker John Boehner, R-Ohio, sent a letter to the president asking him to address specific questions about U.S. interests in engaging militarily in Syria: "Having again determined your red line has been crossed, should a decisive response involve the use of the United States military, it is essential that you provide a clear, unambiguous explanation of how military action - which is a means, not a policy - will secure U.S. objectives and how it fits into your overall policy," Boehner wrote.
"It is essential you address on what basis any use of force would be legally justified and how the justification comports with the exclusive authority of Congressional authorization under Article I of the Constitution," he continued.
High-ranking members of Congress will be briefed by the White House via conference call Thursday on the Syria intelligence and military options and policy objectives, CBS News has learned. Senior officials tell us these consultations with continue "in the days to come."