Recently President Donald Trump authorized a missile attack on a Syrian air force base in retaliation for the Assad regime’s use of chemical weapons in the ongoing Syrian civil war. Republican Senator Rand Paul was quick to criticize the leader of his party for violating the U.S. Constitution, since he neither made a formal declaration of war nor received Congress’s approval.

Russia claimed that the Trump-authorized attack violated international law, since it was neither defensive nor proportionate to any harm done to U.S. geopolitical interests. President Trump defended the attack, claiming that it is in the “vital national security interest of the United States to prevent and deter the spread and use of deadly chemical weapons.”  

Despite Trump’s past tweets that the U.S. should “stay the hell out of Syria” or “many very bad things will happen,” he’s decided that the U.S. should now back up international law—namely the Geneva Protocol which Syria’s use of gas weapons contravenes—with U.S. military might.  

So, does the U.S. president have the authority to attack a sovereign nation without Congressional approval? Does such an attack go against international law?  Does it matter? They are not easy questions to answer and the answers you get clearly depend on whom you ask.

Just war theorists like St. Augustine and Thomas Aquinas claimed that the jus ad bellum (“right to go to war” in Latin) has five conditions:

  1. Proper authorization or formal declaration.
  2. Just cause or right intention.
  3. Likely to achieve the intended result.
  4. Violence inflicted is proportionate to the violence committed by the other side.
  5. All non-violent and diplomatic options are exhausted, so that it is a last resort.

There are several decades of precedent in support of a president’s authority to unilaterally launch attacks against foreign enemies without Congressional approval. Article I, section 8, clause 11 of the Constitution (the War Powers clause) puts the power “to declare war” in the hands of Congress, but this hasn’t happened since World War II.

According to the War Powers Act of 1973, the president must inform and consult with Congress within 48 hours of using military force. Also, he cannot keep troops in a foreign country for more than 60 days without congressional approval. But this doesn’t undermine the authority of a president to act initially without Congressional authorization. As the saying goes, you can’t win a war by committee.

President Obama notoriously sought Congressional approval for Syrian intervention in 2013 (Authorization for the Use of Military Force Against the Government of Syria to Respond to Use of Chemical Weapons) and was denied it.  In a speech, Obama stated that receiving authorization was unnecessary, but made any intervention “stronger” and “more effective” by presenting a united front: “[W]hile I believe I have the authority to carry out this military action without specific congressional authorization, I know that the country will be stronger if we take this course, and our actions will be even more effective.” When Obama decided to intervene in Libya, he completely bypassed any authorization, insisting that it was in the “national interest.”  

In my 2013 book Philosophical Pragmatism and International Relations: Essays for a Bold New World, I defined an international affairs pragmatist as someone who “forego[es] uncompromising values and grand theories in international affairs, embracing instead a situationally-specific approach to understanding and addressing emerging global problems.” In short, a pragmatist in international affairs is part theorist, part practitioner, and all around global problem-solver.

Maybe Trump is coming into his own as an international affairs pragmatist, seizing the authority to use military force when the situation demands it (to solve the Syria problem?). The most pragmatic thing to do, at least in cases involving the use of biological and chemical weapons, might just be to act first, get Congressional permission later.