The word on Syria is that American firepower is nearby, and ready to act if it is called upon.
A senior administration official tells CNN the U.S. is working with its European allies to build a consensus on what to do next about Syria.
Within days, President Obama's national security team will present him with its final, detailed options in response to allegations that the Assad regime used chemical weapons on its own people, which Secretary of State John Kerry called "a moral obscenity."
The White House is already making the case for taking action against Syria.
According to Secretary Kerry, "President Obama believes there must be accountability for those who would use the world's most heinous weapons against the world’s most vulnerable people."
Hence, “if the President gives the order, a senior defense official says four Navy destroyers in the Mediterranean Sea could execute a mission within hours. U.S. and British submarines are also likely nearby, all armed with cruise missiles,” reports CNN’s Chris Lawrence.
“The options are not designed to overthrow Assad's government, but send a message and deter any further use of chemical weapons, President Obama's ‘red line.’”
President Obama is now under pressure to keep his word and support his ultimatum. "Any time you throw down the diplomatic gauntlet, your words have repercussions,” Council on Foreign Relations president Richard Haas says.
While the U.S. is consulting with allies for a plan of action, as Lawrence reports, officials say it may not need a formal coalition to execute the response.
Follow along at CNN.com for developments.
International eyes remain on Syria, where anti-regime activists say hundreds were killed in an alleged massacre.
At least a thousand victims, many of them women and children, are reported dead in a possible chemical weapons attack near Damascus.
Disturbing images from that alleged attack continue to call more attention to the region, raising questions, once more, about President Barack Obama's "red line."
State Dept. Spokeswoman, Jen Psaki addressed the situation to the press, saying “the president has directed the Intel community to, here in the United States, to urgently gather additional information. That is our focus on this end.”
“The U.N. is asking the Syrian government to allow a chemical weapons inspection team to investigate,” reports CNN’s Jill Dougherty.
“U.S. officials say, so far they, cannot ‘conclusively determine’ whether chemical weapons were used. And they're not saying exactly what President Obama would do if they were.”
If these reports are found to be true, Psaki said “this would be an outrageous and flagrant escalation of the use of chemical weapons” by the regime and “the president has a range of options to consider” in that case.
Just last August, President Obama drew his red line, saying: "A red line for us is we start seeing a whole bunch of chemical weapons moving around or being utilized. That would change my calculus.”
But Senator John McCain argues that means nothing to Syrian President Bashar al-Assad.
Sen. John McCain told CNN, “The president of the United States says, that if he uses these weapons that it would be a quote "red line and a game changer". He now sees that as a green light, and that is the word of the president of the United States can no longer be taken seriously.”
McCain believes it's time to take military action, but the Chairman of the Joint Chiefs of Staff, Gen. Martin Dempsey urges caution.
"The use of U.S. Military force can change the military balance, but it cannot resolve the underlying and historic ethnic, religious and tribal issues that are fueling this conflict."
The White House is now definitively saying that it is clear that chemical weapons were used in "small amounts" on the Syrian people.
The big question raised now is how forcefully will the White House respond? Frederik Pleitgen is following the developments live in Damascus.
“The big concern here for the Syrian government is of course, or would be, the establishment of a no-fly zone here in this country,” Pleitgen reports.
“Right now, the Syrian government believes it has the momentum on the battlefield. But of course, increased U.S. Involvement could quench that.”
U.S. intelligence officials say there is so far no evidence of chemical weapons used in Syria, but they are conducting their own investigation as to what happened there, Barbara Starr reports. CNN has learned new details about how the CIA is trying to find answers, including information that intelligence officials are talking to rebels and defectors to learn what they know, she says.
Officials tell CNN, military analysts are also looking at reports from Syrian doctors and videos from the attacks to see if the symptoms and conditions of the patients in them match those of a potential chemical attack. They are investigating satellite imagery to identify movement of chemical weapons and intercepting cyber chatter about attacks as well, Starr reports.
“Now, officials tell us, because the U.S. has no operatives and no U.S. military personnel on the ground inside Syria, this is going to be very tough to prove," Starr says. "And it may take them some time, if ever, to figure out exactly what happened here.”
There is a "high probability" that Syria deployed chemical weapons in the ongoing civil war, but final verification is needed, the chairman of the U.S. House Intelligence Committee told CNN on Tuesday.
"I have a high probability to believe that chemical weapons were used," Chairman Mike Rogers (R-Michigan) told CNN's Wolf Blitzer. "We need that final verification, but given everything we know over the last year and a half, I would come to the conclusion that they are either positioned for use, and ready to do that, or in fact have been used."
Rogers' statement comes as the specter of chemical weapons attacks in the Syrian civil war emerged Tuesday, with the government and rebels each blaming the other for using such munitions.
This morning on "Early Start," CNN's Ivan Watson reports on the conflicting accusations of chemical weapons use.
READ MORE: Game-changer: Syria's 'probability' of using chemical warfare
The violence in Syria rages on with the potential threat of the Syrian regime using chemical weapons on its people. That threat has forced U.S. and NATO forces to rely on rebels to help secure stockpiles. CNN’s Brian Todd is following that part of the story.
“Even if Bashar al-Assad doesn't use chemical weapons in this civil war,” Todd says, “there's enough chaos afoot to alarm western officials about what may happen to those munitions.” According to top diplomats and a senior U.S. official, “the U.S. and its allies are using defense contractors to train Syrian rebels how to secure chemical weapons stockpiles. Our sources say the training's taking place in Jordan and Turkey. They tell us the Syrian rebels are being trained on how to monitor and secure stockpiles, but also on handling the weapons sites, and the weapons materials.”
One objective in training the Syrian rebels is to try to get real-time surveillance of Syria’s chemical weapons sites, Todd reports. But Todd says this may still be cause for concern. “Syrian rebel forces are a confusing mix; moderate freedom fighters, battling alongside hard-line jihadists, some of whom are suspected of terrorist ties."
Philip Mudd, a former CIA and FBI Counter Terrorism Official, sums it up. “When you've got roughly 10-percent of the opposition in groups that the U.S. government is declaring as terrorist groups, you've gotta be concerned they've infiltrated the groups that we're trying to train,” Mudd says. “There's ways around that, but in any case like this, there's a lot of risk."