At National Review, Andrew McCarthy contends that President Trump’s decision to pull out of the Iran nuclear deal is not an example of America going back on its word:

The JCPOA did not represent America’s word, it represented Obama’s word. Our Constitution and our laws are no secret. Our European allies know full well that a president has no power unilaterally to bind the United States to an international agreement. We give our word when we enter a treaty or enact legislation that cements commitments. Obama did not seek to make his deal a treaty precisely because he knew America was not giving its word — the public did not support the deal, which would have been roundly defeated if subjected to the Constitution’s process for ratifying international commitments.

McCarthy is right about that, but there are a couple of problems:

• Ratification of a treaty requires the approval of two-thirds of the Senate, and it’s nearly impossible to get that level of support for anything from the polarized Senate anymore. Indeed, George W. Bush relied a lot on non-treaty “executive agreements” to get business done abroad. As a practical matter, America may not be currently capable of giving its word to any trustworthy degree if treaties are near-unobtainable and executive agreements are so easily undone.

• The Constitution also gives Congress the capacity to declare war, and yet presidents — Democratic and Republican alike — pretty universally ignore any constraints on their ability to commit American forces to violent action around the world. And McCarthy has been pretty sanguine about that fact. Here he is writing in 2011:

When the system is working properly, the president must get Congress’s approval to initiate an unprovoked war. As a practical matter, however, the president cannot be stopped from doing this absent a strong, accountable Congress that is willing to flex its constitutional muscles … We’re a body politic, not a body legal.

McCarthy essentially admits the system does not work as it should, and shrugs.

What all this boils down to is this: As a practical matter, the American president has nearly unlimited power to make war — and very limited, easily reversed power to make a lasting peace.

That’s a recipe to get more war than peace.