Lawmakers are divided over the constitutionality of a U.S. missile strike carried out against the Syrian government on Thursday.

AP Photo/Evan Vucci

Though President Donald Trump's authorization of the attack — which targeted a Syrian government air base — was applauded by a mixed bag of moderate Republicans and Democrats, others in Congress have questioned the constitutionality of this military action.

Trump ordered the missile strike two days after a chemical weapon, reportedly deployed by the Syrian regime, killed at least 72 people on Tuesday. The attack evoked widespread condemnation and calls for the Trump administration to deliver a "proportional" military response. But there seemed to be a lack of consensus on Capitol Hill as to whether launching about 60 tomahawk missiles at a Syrian air base qualified as proportional.

On the Democratic side, House Minority Leader Nancy Pelosi (D-Calif.) said the attack did appear to be proportional — though she cautioned that Trump would need congressional approval under the Authorization for Use of Military Force (AUMF).

Rep. Adam Schiff (D-Calif.) said in a statement that the missile strike “will not hasten an end to the Assad regime, but it may deter its further use of chemical weapons." He emphasized that the action was not authorized by Congress, though.

"Congress cannot abdicate its responsibility any longer and should vote on any use of force not made in self defense," Schiff said. "This is necessary whether action is taken against terrorist groups or, as here, against regime capabilities."

Other Democrats, such as Rep. Ted Lieu (D-Calif.), voiced unequivocal opposition to the missile strike on the basis of its constitutionality.

On the Republican side, the attack was praised by some of Trump's harshest critics, including Sen. John McCain (R-Ariz.) and Lindsey Graham (R-S.C.).

"Acting on the orders of their commander-in-chief, they have sent an important message the United States will no longer stand idly by as Assad, aided and abetted by Putin's Russia, slaughters innocent Syrians with chemical weapons and barrel bombs," the senators said in a joint statement Thursday.

But again, there was no party consensus on the action.

The War Powers Act of 1973 limits the authority of the president to go to war without approval of congress, unless it is in response to a direct threat to United States citizens. Though the United States has been bombing in Syria since 2014, the legal authority to do some comes from a 2001 Authorization for Use of Military Force, which only applies to members of Al-Qaeda and its affiliates. There's no authorization on the books for bombing the Assad government. 

Certain Republican lawmakers such as Sen. Rand Paul (R-Ky.) joined calls for congressional authorization for such attacks, tweeting that "prior interventions in this region have done nothing to make us safer and Syria will be no different."

Sen. Mike Lee (R-Utah) also said the president would need congressional approval it the White House intends to "increase use of military force in Syria."

Though lawmakers are not in full consensus about the constitutionality of authorizing such a military strike in the absence of congressional approval, it does appear that support for this effort to retaliate against the Syrian regime in light of Tuesday's chemical weapons attack has crossed party lines.