A red line-what is it, has it been crossed and what might that mean as far as the U.S. government is concerned.
The red line we are talking about today involves Syria.
A red line for us is we start seeing a whole bunch of chemical weapons moving around or being utilized.
President Obama said that last August.
A recent attack that reportedly killed more than 1300 people is suspected of having crossed the president's red line.
Many governments and organizations consider chemical weapons worse than conventional weapons like bombs or guns.
The United Nations describes chemical weapons as a crime against humanity.
Although some analysts say the impact of conventional weapons are just as awful for victims.
The idea of a red line is that once it's been crossed, the person or country that's set it could take action.
Chris Lawrence examines what steps the U.S. could take next.
Within days, President Obama's national security team will present him with its final detailed options, and the administration is already making the case for taking action against Syria.
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.
Secretary of State John Kerry accused the Assad regime of gassing its own people.
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.
The extremely accurate Tomahawks can be fired from 500 miles away, with an ability to change course in midflight.
The potential targets include the delivery systems that can be used to launch weapons.
Militia training camps being run by Bashar al-Assad.
And most importantly, the Syrian government's command and control centers.
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.
In any time you throw down a diplomatic gauntlet, you words have repercussions.
The president is under some pressure to back up his own ultimatum.
And while the U.S. is consulting with allies, officials say, it may not need a formal coalition to execute the response.
Chris Lawrence, CNN, the Pentagon.