Obama: 'We have not yet made a decision' on strike against Syria

President Obama insisted no final decision has been made on a military strike against Syria even while saying a strong signal must be sent in response to that regime's use of chemical weapons.

"We have not yet made a decision, but the international norm against the use of chemical weapons needs to be kept in place," Obama said in an interview with "PBS NewsHour."

He also highlighted the legal justification the U.S. would use to support a strike, saying the use of chemical weapons "violates Geneva Protocols," and that if the U.S. gets involved it intends to show Syrian forces it had "better not do it again."

The president also said that the U.S. had definitively "concluded" that the Assad regime was responsible for last week's chemical weapons attack in Syria, becoming the highest-level U.S. official to assert so. Obama added that while he had solicited "options from our military," he was not yet set on direct military engagement with the Assad regime.

Obama admitted that a limited strike would not "solve all the problems inside of Syria" and "doesn't obviously end the death of civilians inside of Syria." But he said that the U.S. has been "restrained" because he has determined that getting involved in the fight between the regime and rebel forces would be counterproductive.

"What I have concluded is that a direct military engagement, involvement, with a civil war in Syria would not help the situation on the ground," Obama said.

At the same time, the massive chemical weapons attack on a suburb of Damascus has changed "some of our calculations," Obama said.

"We want the Assad regime to understand that by using chemical weapons on a large scale against your own people, against women, against infants, against children that you are not only breaking international norms and standards of decency, but you are creating a situation where U.S. interests are threatened," Obama said. "And that needs to stop."

Congressional leaders on both sides of the aisle have said that Obama needs to make the case to Congress for any military action in the country.

In a letter to the president on Wednesday, Speaker John Boehner (R-Ohio) said that briefings provided to top lawmakers have not done enough to answer concerns from the legislative branch.

“I respectfully request that you, as our country’s commander-in-chief, personally make the case to the American people and Congress for how potential military action will secure American national security interests, preserve America’s credibility, deter the future use of chemical weapons, and, critically, be a part of our broader policy and strategy," Boehner wrote.

Foreign Policy reported Tuesday that the U.S. intelligence services intercepted a panicked call between the Syrian Ministry of Defense and a chemical weapons unit shortly after the attack, convincing the administration of the Assad regime's culpability — while raising questions about whether a rogue unit might have been to blame.

Administration officials plan to publicly present a report outlining their intelligence findings within the week, as well as brief congressional leaders.

More than 100 House members have demanded a congressional vote in a separate letter to the president, although Boehner stopped short of that demand.

A U.S. official speaking to the Los Angeles Times said that Obama is seeking a strike on Syria "just muscular enough not to get mocked."

"They are looking at what is just enough to mean something, just enough to be more than symbolic," the official told the paper, giving credence to similar reports describing a limited military strike in the aftermath of last week's alleged chemical weapons attack.

NBC News reported earlier this week that the administration would launch three days of missile strikes, while CNN cited a senior administration official saying that the White House wanted to conclude any action before the president departs for the G-20 summit next week.

The New York Times also reported that the initial target list drafted by the Pentagon had fewer than 50 sites. The Pentagon has moved four U.S. Navy destroyers off the Syrian coast, which can launch low-altitude cruise missiles at selected sites.

Updated at 7:12 p.m.