Are Americans ready to deal with Syria's chemical weapons?

If President Obama were to deploy military force in Syria – right into the heart of the Middle East – would it be on moral grounds or in America’s self-interest?

The rationale for any US intervention in Syria may be important for Americans to know sooner rather than later. Intense fighting has erupted around Damascus. President Bashar al-Assad appears dangerously cornered. On Monday, Mr. Obama seemed to tip his hand more strongly on the moral versus self-interest question. He warned Mr. Assad that “there will be consequences and you will be held accountable” if the Syrian Army uses its stockpile of chemical weapons.

The weapons pose little or no threat to the American homeland. Yet Obama’s moral stance on Syria’s weapons of mass destruction – similar to his tough warnings to Iran about building a nuclear bomb – has pushed him to promise a response in Syria that is only lightly veiled as one involving force. That contrasts with no threat of US force to end Assad’s killing of tens of thousands of civilians.

Obama’s last use of force against a country started with a moral goal – to protect mass slaughter in the Libyan city of Benghazi by Muammar Qaddafi’s Army in 2011. As that goal was achieved, American forces then went further. They flushed out Mr. Qaddafi from hiding, resulting in his killing. Today, Obama cites the military result in Libya as a victory for the advance of democracy in the Middle East – highlighting another moral purpose in his strategy toward the region.

In recent decades, the United States has often conflated national interests with moral purpose. The confusion can often result in difficult debates at home about the best use of resources.

When Iraq invaded Kuwait in 1990, President George H.W. Bush argued for an invasion on the grounds of both protecting Persian Gulf oil supplies and defending the principle of national sovereignty in the world. In 2001, his son led a post-9/11 invasion of Afghanistan both to capture Al Qaeda leaders and also to save that country from Islamic autocracy and to uphold women’s rights. Then in 2003, he led the US in an invasion of Iraq, both to promote democracy in the Middle East and to prevent Iraq from ever helping Al Qaeda obtain weapons of mass destruction for use in another terrorist attack on the US.

The US posture toward Iran’s nuclear program remains mainly a moral one: to prevent a nuclear arms race in the Middle East and protect Israel. To a much lesser degree, Obama cites human rights violations in Iran. But with Iranian missiles possibly able to reach US troops in Europe soon, Obama is deploying a missile shield in the region. And oil supplies also remain a concern.

Now Syria poses yet another possibility of an American president needing to clarify his goals in the use of force. The US has spotted the movement of chemical weapons by the Assad regime. And Russians report Assad seems desperate about his future, trapped by advancing rebel forces and his own Alawite minority that insists he not flee.

A US president not only needs to sort out the moral goals from the national interests in such situations, he also must take heed of public opinion. Polls show Americans eager to exit Afghanistan and avoid intervention in Syria. Yet more than half want the US to stand up to Iran.

America’s historical role as both the world’s occasional moral policeman and a country that pursues its narrow interests is in need of constant reevaluation. Syria’s near-collapse is a prime moment to do so again. A clear speech on Syria by Obama, followed by a debate in Congress, might prevent any unwise steps by the US in Syria.