President Bush and Iraqi Prime Minister Nouri al-Maliki issued a joint letter in November. On the surface, the "Declaration of Principles" appears as a mutual "expression of friendship," as it has been characterized by administration officials.

The "Declaration of Principles" includes language that seems run-of-the-mill. The United States will help get Iraq into the World Trade Organization. The two countries will engage in scientific and cultural exchanges.

But it also includes a provision that promises to maintain the stability of Iraq's government from "internal and external threats." This sentence is raising alarms for some U.S. lawmakers.

Any such agreement would be considered a treaty by many legal experts. And under the U.S. Constitution, treaties have to be ratified by Congress.

"The declaration of principles would appear to commit the United States to keeping the elected Iraqi government in power against internal threats," says Kenneth Katzman, a Middle East analyst at the Congressional Research Service. "I leave it to the lawyers to determine whether that's the definition of a treaty or not but it certainly seems to be - is going to be - a hefty U.S. commitment to Iraq for a long time."

Such a hefty commitment would be unprecedented in the history of American foreign policy.