Some members of the Senate are taking the possibility that Trump will order an attack on North Korea seriously:

A group of Democratic senators is warning President Trump that he lacks the “legal authority” to carry out a preemptive strike on North Korea, amid questions over whether the White House is considering a risky “bloody nose” attack.

In a letter to be sent to Trump on Monday, the 18 senators said they are “deeply concerned about the potential consequences of a preemptive military strike on North Korea and the risks of miscalculation and retaliation.” They emphasized that it is an “enormous gamble” to believe that such an action, even if it were modest in scope, would not provoke an escalation from dictator Kim Jong Un.

“Moreover, without congressional authority, a preventative or preemptive U.S. military strike would lack either a constitutional basis or legal authority,” the senators wrote in the letter organized by Sen. Martin Heinrich (D-N.M.), a member of the Senate Armed Services Committee.

These senators are right to be worried about a possible attack, and it is to their credit that they are speaking out against it early on. Most members of Congress prefer to shirk their responsibilities in these matters for as long as possible, and it is usually much easier for them to defer to the president, so it is worth noting when some of them don’t do that. They are also right that ordering an attack without Congressional authorization would be a violation of the Constitution, and their letter is an overdue sign of resistance from Congress to presidential warmaking. It would be even easier for members of Congress to duck the question of the legality of an attack, and it is significant that the senators make a point of stating clearly that the president has no authority to do this on his own.

More than sixteen years of ceaseless foreign wars, including a few without any Congressional authorization or debate, have accustomed Americans to the idea that presidents are permitted to start wars whenever they feel like it, but they aren’t. The letter from the 18 senators is a good beginning in challenging the executive’s ongoing excesses in matters of war, but to have the desired effect there will also need to be a sustained effort to oppose the unauthorized, illegal wars in Syria and Yemen as well.