WITH AMERICAN armed forces in the Persian Gulf seemingly poised for a military strike aimed at driving Saddam Hussein's troops from Kuwait, the American political system is reacting as it has since the advent of the Constitution: Congress is worrying about how best to exercise its authority over the armed forces, and President Bush, like so many presidents before him, is acting as though the Congress doesn't have any authority to exercise.

Many senators and representatives insist that the president must consult with them, and possibly gain their explicit approval, before launching an attack. Publicly, the White House has been noncommittal. But one recent news report quoted a presidential aide as dismissing the congressional role this way: "They will receive the usual phone calls after the bombs start dropping."

Does such cavalier treatment fly in the face of the Constitution, which gives Congress the sole power to declare war? Critics who would make this constitutional case are looking at the wrong clause. In this engagement, as in most of our nation's military history, the true rein on executive power lies not in the declaration clause but in Congress's control of the power of the purse. This, in the Founders' scheme, was the ultimate congressional check on executive military adventurism.

While debate over the proper allocation of the war power between the president and Congress has raged or simmered throughout most of our history, the fact is that from George Washington's undeclared wars with the Indian tribes to Ronald Reagan's intervention in Grenada, presidents have sent American forces into battle without seeking prior congressional approval. And despite a frequent chorus of complaints that its constitutional prerogatives are being ignored, Congress has almost always allowed it. Indeed, the deadliest conflict in the nation's history, the Civil War, was never declared.

Seen against this background, today's congressional cry for a share in any decision on whether American armed forces engage Iraqi troops in a battle to liberate Kuwait is not an unusual feature of American history. The continuing political turmoil is the result of an awkward but sensible compromise built into the system by the Founders who laid down the original Constitution in 1787. The Constitution establishes the president as commander-in-chief, but reserves to Congress the authority to declare war, to regulate the armed forces and to provide for their support. Those who wrote and ratified the Constitution thought this system adequately provided for defense of the nation's interests while striking a balance that would not permit either the president or Congress to decide alone to begin a war.

Over the nation's history, of course, things have not been quite so simple. Presidents have quite frequently decided alone when to fight, and rarely because foreign invaders have forced the choice. In former times, with lines of communication long and indirect, the president would often give the troops their marching orders and have them on their way before anybody in Congress was the wiser. This enabled him to present Capitol Hill with a fait accompli, and, in effect, to dare the legislators to do anything about it. Sometimes, moreover, an individual military commander would act on his own initiative, thus putting the president to the choice of backing the troops in the field or backing down -- and presidents have always hated backing down.

With the advent of instantaneous communication, particularly the mass media, it is harder for modern presidents to do what was done in the past. In this sense, the fact that Congress throughout the 19th and much of the 20th century was able only to react to presidential military actions might be seen as a technological artifact. In the late 20th century, secret military operations are almost impossible to undertake; the Persian Gulf war, if there is one, will plainly be televised, and Congress, if it wants to, will be able to seek a confrontation with the president from the time of the opening salvos. The argument that the president must consult with Congress, and perhaps obtain its permission, before launching an attack on Iraq's forces rests on two propositions: first, that under the Constitution, U.S. forces cannot undertake such a fight without a formal declaration of war, a power vested solely in the Congress; and, second, that an attack on Iraqi troops, or even an extended "trip-wire" mission, requires congressional permission pursuant to Section 5 of the War Powers Resolution of 1973.

The constitutional argument, not to put too fine a point on it, is almost certainly wrong. There is nothing in the history of the ratification of the Constitution to suggest that the Founders imagined that a congressional declaration of war would be needed whenever American troops fought an engagement. On the contrary, at the time that the Constitution was adopted, a declaration of war was not considered necessary before a sovereign state could engage in war. The declaration carried with it important consequences for the law of nations but had little practical significance in domestic law; in particular, it had nothing to do with the ability of a sovereign nation to defend its interests.

The Founders were concerned, moreover, that the president's ability to act swiftly in a crisis not be hobbled by the necessity of gaining prior legislative approval for his orders. During the Revolutionary War, a committee of the Continental Congress took it upon itself to issue orders to Gen. Washington in the field. Under the Articles of Confederation, which governed the new nation until 1787, no independent executive existed and Congress possessed the power to conduct hostilities. Dissatisfaction with these precedents was the principal motivation for the Constitution's designation of the president as commander-in-chief and the reduction of the role of the legislature to regulating the armed forces and declaring war.

But it is hardly the case, although some have so argued, that if the president as commander-in-chief can order troops into battle without a declaration of war, the power to declare war becomes a nullity. Quite apart from its international-law significance, the declaration power was designed to provide a measure of control over the president's ability to launch an offensive war -- to make America the belligerent who started things. It is the decision to begin a war where none exists that the Congress under the Constitution must share.

The difficulty comes in working out what constitutes an offensive war that the Congress must declare and what amounts instead to an action in defense of the nation's interests that the president can undertake without prior approval. The role of the United States in the world has grown beyond anything that the Founders could have anticipated, and one might point to "vital interests" that are very far removed -- both geographically and politically -- from what the designers of the divided war power must have had in mind.

Moreover, even granting the distinction between offensive wars and defenses of the nation's interests, one might argue that an offensive war is precisely what the United States is poised to launch in the Persian Gulf. But one must be careful of semantics.

It is not possible for President Bush to start a war in the Gulf, because the Gulf war has already begun: Saddam Hussein started it when he invaded Kuwait. At best, then, it might be said that American forces are poised to enter a war that is already underway, at the invitation of one of the belligerents, and perhaps (although the matter is not yet decided) at the invitation of the United Nations as well.

The precedents, although not always clear-cut, tend to lean the president's way; if Bush is acting against the dictates of the Constitution by ordering American forces to defend another nation, he has plenty of company. President Tyler, for example, sent U.S. warships to protect Texas before it was part of the United States, and President Roosevelt, prior to formal American entrance into World War II, sent forces to defend Greenland and Iceland and ordered our fleet to sink German U-boats on sight. This history (along with panicky finger-pointing following popular disenchantment with U.S. participation in the war in Vietnam) confronted Congress when, in 1973, it forced the War Powers Resolution (sometimes wrongly referred to as the War Powers Act) on a weakened President Nixon. The resolution's supporters described it as an effort to meet the demands of a modern superpower while preserving the congressional prerogative to decide when the United States should fight an offensive war. Opponents called it an inexcusable legislative usurpation of the powers of the commander-in-chief.

The theory of the resolution is that the United States gets embroiled in foreign military adventures because the president does not seek congressional advice or approval. Secretary of Defense Richard B. Cheney, while serving in Congress, described the statute as "an effort to keep us out of the next war based on a misperception of how we got into the last one." For whatever lessons one might draw from the Vietnam adventure, one simple truth is that Congress allocated funds for its prosecution, year after year after year.

The War Powers Resolution requires congressional approval whenever U.S. troops spend more than 60 days (90 days in certain circumstances) engaging in hostilities, deploying into areas where hostilities are imminent, or serving in a foreign nation "while equipped for combat." If the War Powers Resolution is constitutional -- a matter on which legal scholars are sharply divided and on which no court has yet ruled -- then the president plainly needs congressional permission in order to conduct an extended campaign in the Persian Gulf.

That the resolution burdens the president's warmaking authority is undeniable, and if the resolution absolutely forbade any use of American forces without prior congressional approval, it would represent a flagrant violation of the separation of powers. Even as it stands, its constitutional validity hangs at best by rather a thin skein.

The commander-in-chief clause, almost certainly designed with George Washington in mind, made the president the chief general of the armed forces, with the sole authority to make decisions about day-to-day military operations. Naturally, the president's authority under the clause is subject to a degree of congressional regulation. However, those who seek the source of regulatory power in the declaration clause are looking in the wrong place.

A declaration of war, if one takes seriously the proposition that American forces cannot fight without one, is an either/or decision -- one is in a state of war or one is not. What Congress seems to be doing instead is using its constitutional authority to declare war as a wedge to have a part in something quite different -- the conduct of a military campaign. The power that Congress insists on trying to exercise is the power to decide, in consultation with the president, whether and how American military power should be projected in a particular crisis -- what is known as micromanagement. Micromanagement is what the Continental Congress did when it sent orders to Gen. Washington. It is what Congress did under the Articles of Confederation, before the adoption of the Constitution, when there was no independent executive and the legislature possessed all warmaking authority. And it is exactly what the division of the war power under the Constitution was designed to prevent. As the Supreme Court noted nearly a century ago: "The President cannot, under the disguise of military orders, evade the legislative regulations by which he in common with the Army must be governed; and Congress cannot in the disguise of 'rules for the government' of the Army impair the authority of the President as commander in chief."

If it wishes to act consistently with the original constitutional design, Congress should leave military strategy to the president and reserve to itself the ultimate go/no-go power, which it needs no special War Powers Resolution to enforce. At any time that enough members care to do so, the Congress can refuse to fund a war that the president wants to fight. If opponents of a particular deployment are unable to muster the votes to make the president stop, then the fighting, or risk of fighting, will continue. That is the constitutional design, and it is a sensible one, for it combines the efficiency of a single operational decision maker with an effective veto by the legislature.

So senators and representatives are right to insist that they, too, hold a share of the warmaking power. They are wrong, however, to suppose this entails a presidential obligation to consult with them about operations. Congress can halt a war -- any war -- whenever it pleases. It need only refuse to pay. Congress can also adopt a charter to govern the operations of the armed forces. What Congress cannot do is claim the authority to micromanage military hostilities that it makes no effort to halt. As the Founders well understood, wars that are fought by committee rarely succeed.

Stephen Carter, a professor of law at Yale University, writes frequently on the constitutional separation of powers.