President Obama has chosen his words very carefully since authorizing military action in Libya.
He announced the first strikes from Brazil Saturday during a five-day trip through Latin America and described a "limited military action."
Two days later in Chile, he talked about "very short time frames" and "days not weeks." And there was equal caution in El Salvador, where he steered clear of any mention of the word "war."
The administration has used such language not only to calm political fears that the United States is on the brink of an open-ended military conflict, but to neutralize arguments from Congress and critics that the president has exceeded his constitutional authority.
Obama officially informed Congress of the attacks two days after the conflict began, saying he had acted pursuant to his "constitutional authority" in a manner "consistent with the War Powers Resolution."
But critics almost immediately questioned whether Obama had the constitutional authority to launch the attack. The actions in Libya reignited a long-standing debate about the scope of executive power to use force without prior congressional approval.
A top Congressional confidant of House Minority Leader Nancy Pelosi, California Democrat Rep. George Miller, suggested this morning that President Obama acted outside his Presidential authority by engaging in military action without consulting Congress.
"Well, I'm one of those people who believe that when you're not defending the shores of the United State, you have an obligation to come to the Congress and ask for permission," said Miller on MSNBC Thursday.
He later said he thinks Obama would have gotten permission from Congress.
"The constitutional lines defining the president's authority to use military force without congressional authority have never been clearly defined and remain subject to substantial debate," Matthew Waxman, an expert on national-security law at Columbia Law School, said.
While the Constitution gives Congress the power to "declare war," it also outlines that the president is the commander in chief of the Army and Navy.
"This division of authority doesn't provide much guidance," Waxman said, "especially with respect to limited uses of force."
There have been numerous attacks -- including the Korean War, the Kosovo intervention in 1999 and the use of force in Haiti -- that were launched without congressional authorization. Each conflict sparked a debate about the scope of the executive's power.
Harvard Law professor Jack Goldsmith weighed in this week, saying he believes the Libyan action is constitutional.
Goldsmith, who worked in the Bush administration, noted that a combination of "indeterminate constitutional language" and the courts' having never resolved the question about the scope of the president's power to use force without authorization gives the executive "very broad discretion."
During the Vietnam conflict in 1973, Congress passed the War Powers Resolution in part to make clear that there should be more limits on the president's power to use military force. The act allows the president to use military force without congressional authorization for 60 days unless Congress permits otherwise.
It requires the executive to report to Congress within 48 hours of introducing armed forces. Obama referred to the resolution in his letter to Congress two days after the Libyan conflict began.