"It should be more easy to get out of war than into it," Oliver Ellsworth told the Philadelphia Convention on August 17, 1787.

With the malignant political genius of the nuclear age, Americans have reversed that order of things.

War now takes but a wave of the executive hand, but seems impossible to end. Congress authorized military action against Al Qaeda in 2001, and against the government of Iraqi dictator Saddam Hussein in 2002. Hussein is long gone, and Al Qaeda may or may not still exist; legally, however, these wars grind on, the longest-running pair in American history.

Thursday night, without a word to Congress or the public, the Trump Administration impulsively began a third conflict. Neither of the existing authorizations could even remotely be said to authorize Thursday's attack on Syria. We have no way of knowing whether it was a brief executive whim or the beginning of a third nightmare that will outlast the other two.

Here is President Trump's statement of the aims of the missile strike: "I call on all civilized nations to join us in seeking to end the slaughter and bloodshed in Syria, and also to end terrorism of all kinds and all types." His message to Congress is pure boilerplate: “I acted in the vital national security and foreign policy interests of the United States, pursuant to my constitutional authority as Commander-in-Chief and Chief Executive.”

I have no idea what policy in Syria would be effective in protecting that country's people from their murderous government, ending the country's murderous civil war, blocking increased influence by Iran and Russia in the Middle East, and stemming the rise of the Islamic State. I do not know which of the armed groups fighting against the government of Bashar al-Assad are fighting for something like democracy and which are seeking religious or ethnic dictatorships. I can't tell you how a global superpower can affect the political and military outcome of a multi-sided civil war without itself becoming involved in ground operations and even occupation—and dangerous conflict with other major powers.

Wise heads in the Pentagon and the National Security Council may actually have a plan; they may know friend from foe; they may have imagined the next step, and the next, wargaming intelligent American responses in the likely event that things in Syria do not immediately fall into place.

But I don't know. No one outside the small world of national security knows. The president has not even pretended to tell us whether he has any plan at all, and if so, what it is.

Indeed, from his statements on Thursday, it seems at least possible that, moved by the horrific video images of Syrian children suffocated by a gas attack, Trump simply decided to "do something" because, as he said in his statement, "No child of god should ever suffer such horror."

The impulse to act without thinking would be understandable. Careful planning and clarity of purpose aren't easy in a fast-moving international situation. But the framers of the Constitution constructed a mechanism to reduce or eliminate the danger that a president would take the nation to war on a fleeting impulse.

They gave the power to initiate war not to the president but to Congress.

Article I § 8 cl. 11 gives Congress the prerogative to "declare war." The powers surrounding that grant suggest that everything about the choice of war is a congressional power. Article II § 2 cl. 1 makes the president "commander in chief of the Army and Navy ... and of the militia”—but the context doesn't suggest that is the power to "command" the entire nation into war. In fact, the original wording of Article I gave Congress the entire power to "make war," with nothing given to the president. The Convention amended the words to "declare war," in order to give the president the narrow power to, in the words of Madison's Notes, "repel sudden attacks."

Roger Sherman of Connecticut objected that the wording gave the  president too little power. He was rebuked by Eldridge Gerry of Massachusetts, Oliver Ellsworth of Massachusetts, and George Mason of Virginia, who all agreed that reposing the war choice in the executive would be dangerous.

"Mr. GERRY," the Notes record, "never expected to hear, in a republic, a motion to empower the Executive alone to declare war." Though often flouted by overreaching presidents and craven Congresses, that division of power remains the law of the land.

Unless the United States or its vital interests are under attack, the president must ask Congress before using military force against another country. The restriction may seem largely formal—the last time Congress actually turned down such a request was when the Senate blocked the Armed Ship Bill requested by President Woodrow Wilson in 1917. But it's not an empty formality. A president who wants to take the nation into war should be able to put the request in writing, explain it to the nation in his own words, and send diplomats and military leaders to lay out the policy behind the request, the scope of the conflict it is likely to produce, and the criteria by which the nation can measure success.

The action in Syria does not respond to "a sudden attack" on the United States. Nor can the Administration even try to hide behind the Obama-era dodge that it is not sending U.S. forces into "hostilities." If that rationalization ever served, it doesn't do so here. While the renewed use of chemical weapons in Syria may be an emergency, I haven't yet heard an explanation of why the United States cannot do what any prudent power would—follow its own laws and international law, persuade and inform its own people, seek the assent of the United Nations Security Council, consult its allies, and set forth its war aims.

In retrospect, it America's failure to intervene in Syria in 2013 was probably  a historic mistake.

It was not Barack Obama's mistake alone, but one made by the entire nation. Obama announced his plans but then asked Congress to approve them—precisely as the Constitution requires. His critics portray this request—the one time when Obama actually refused to violate the war powers system of the Constitution—as his personal folly. But members of both his own and the opposition parties in Congress made it known that they would not back his request; many elder statesman opposed the intervention; and national polls showed a solid majority of the public opposed.

After the apparent nerve gas attack last week, the current president issued a grotesquely improper official statement blaming Obama for Assad's recent crime. In 2013, however, private-citizen Trump had loudly and strenuously objected to Obama's planned intervention and demanded the president seek the approval of Congress.

However harshly history may judge the default of 2013, it was a failure not of one leader but of national will. Has the nation regained its will for a prolonged, bloody, and morally ambiguous struggle in Syria? Or will the United States drop the conflict after a few loud booms? That Donald Trump has, for the moment at least, changed his mind is not only of limited constitutional relevance—it also tells us less than nothing about whether the American people understand, accept, and embrace what may be needed for the intervention to succeed.

Harry S Truman was the first American president to commit to a major intervention—in Korea—without even the pretense of congressional approval. Because he had set forth no war aims, he could not resist Gen. Douglas MacArthur's pressure to blunder into war with China. Because he had not obtained Congressional assent, he found himself alone when the war turned dangerous.

If Truman were here to warn Trump, would he, or would anyone in 2017 Washington, even listen? They have not listened to Madison, or Gerry, or Ellsworth, or Mason.