Most worries about Washington’s proclivity for dubious military adventures focus on the imperial presidency. There is certainly good reason to fear an unfettered executive in foreign affairs. But there are instances in which Congress has been the more warlike branch, and we are currently witnessing two examples.

One involves the growing pressure for the United States to take action against Bashar al-Assad’s regime in Syria. The other is the congressional campaign for a more confrontational policy, including the possible use of military force, against Iran’s nuclear program. Although the Obama administration has taken a fairly hard line on both issues, it apparently is not uncompromising enough for Congress.  Led by the Three Amigos in the Senate—John McCain, Lindsey Graham, and Joseph Lieberman—and their hawkish counterparts in the House, a crescendo of calls for new U.S. crusades in the Middle East is rising.

But this is not the first time the legislative branch has taken the lead in getting the country into armed conflicts. Consider two fateful historical instances: the period before the War of 1812 and the run-up to the Spanish-American War in 1898.

The term “warhawk” was in fact coined to describe the militant attitudes of such congressional figures as Henry Clay and John C. Calhoun, who helped push the United States into the War of 1812. The stridency of that faction put constant pressure on James Madison’s administration to confront Great Britain.

Warhawks typically stressed alleged British violations of U.S. territorial integrity and maritime rights on the high seas. They had some grounds for their complaints.  The British Navy was not shy about resorting to “impressment”—stopping U.S. merchant vessels, removing supposed British citizens, and essentially conscripting them on the spot. That would have been irritating enough if those seized were indisputably British citizens. But citizenship was often in question, and it appeared that many of the targets were in fact American citizens

In addition, nearly three decades after the treaty ending the Revolutionary War and recognizing the independence of the United States, British troops still occupied forts in U.S. territory, primarily in what is now Michigan and other portions of the upper Midwest. Angry members of Congress accused those military units of forging alliances with Native American tribes, arming them, and encouraging them to attack American settlements. They contended further that warriors from those tribes often retreated to sanctuaries in British Canada following their attacks.

Yet the focus on such grievances concealed less savory motives for congressional pressure to go to war. Many of the warhawks were motivated by the desire for U.S. territorial expansion. They coveted Canada and recalled that Benedict Arnold’s forces during the Revolutionary War had come so tantalizing close to capturing Quebec, after already taking Montreal. If Arnold’s army had been victorious, the British government might well have had to recognize U.S. sovereignty over that territory. To Clay, Calhoun, and other militant nationalists who displayed early signs of embracing what would later be known as Manifest Destiny, the “liberation” of Canada was unfinished business, and the American republic would not be complete until that land was incorporated into the Union.

Opponents of war with Britain were furious at the apparent hypocrisy of the hawks. Virginia Congressman John Randolph of Roanoke issued a blistering indictment. If the United States went to war, he charged, it “will not be for the protection of, or defense of, maritime rights.” Hunger for Canadian land “urges the war,” Randolph fumed. “Ever since the report of the Committee on Foreign Relations came into the House, we have heard but one word—like the whip-poor-will, but one eternal monotonous note—Canada! Canada! Canada!”

Motivated by national pride pricked by British affronts and an insatiable hunger for Canadian territory, Congress put steadily more pressure on Madison to confront the powerful British Empire. Eventually the warhawks got their wish. Revealingly, the vast majority of the early actions during the ensuing conflict consisted of U.S. offensives into Canada. It is a sobering historical lesson that those offensives largely failed, and the United States came perilously close to losing the war. A low point in American history occurred when British forces captured Washington, D.C., burned the White House and other buildings, and forced the president and the rest of the government to flee. The United States was fortunate to come out of the War of 1812 with essentially a draw.

Eight decades later, another militant Congress prodded a cautious White House to launch a war. This time the target was Spain. Much has been written about the role of the so-called Yellow Press—the Hearst and Pulitzer newspaper chains—in producing highly biased and inflammatory accounts that led the United States into war. But influential members of Congress served as willing allies of that effort. Both President William McKinley and his influential political adviser, businessman Mark Hanna, were reluctant to take the country into war. Pro-war agitators had more of an impact on congressional opinion.

As in the lead up to the War of 1812, there was a major gap between the issues hawks stressed and what appeared to be their real motives. During the mid-and-late 1890s, the Yellow Press and its congressional allies focused on the brutal treatment that Spanish authorities meted out to inhabitants of Cuba, one of the handful of colonies remaining in Madrid’s once vast empire. That treatment was indeed harsh, but it was no coincidence that the most vocal advocates of U.S. support for Cuba’s rebel forces were also advocates of U.S. imperialism. Massachusetts Senator Henry Cabot Lodge asserted that the sympathies of the “generous, liberty-loving” American people were “with the Cubans in their struggle for freedom.” He added that Americans would “welcome any action on the part of the United States to put an end to the terrible state of things existing there.”

But just as the emphasis on the British practice of impressment and the Redcoats’ illegal outposts on U.S. territory served as a fig leaf for the less noble goal to seize Canada, the focus on the Spanish authorities’ atrocities in Cuba concealed a growing desire to seize Spain’s colonies in the Caribbean and elsewhere to increase the reach of U.S. power, especially naval power. To the cheers of congressional warhawks, the main targets once war erupted were Spanish installations in the Philippines and Puerto Rico, neither of which had much relevance to Madrid’s behavior in Cuba.

American forces quickly crushed the decrepit Spanish navy and army units, and the United States acquired the far-flung colonies that Lodge and other imperialists so desired. But the aftermath was not exactly pleasant. Not only did the U.S. victory lead to a prolonged, bloody insurrection by pro-independence forces in the Philippines, but the new U.S. territorial holdings entangled the Republic in an assortment of headaches over the long term in both the Caribbean and East Asia.

Those experiences should be kept in mind as McCain, Graham, Lieberman, and other congressional hawks seek to push the Obama administration into war against Syria and Iran. And that is their goal: in the case of Syria, they and their ideological allies openly call for arming the so-called Free Syrian Army, despite evidence that anti-Western Islamic militants may have a hefty influence in that faction. The Three Amigos have also urged the administration to establish no-fly zones to provide safe havens for civilian refugees and rebel fighters. And pro-war members of Congress have lobbied for air strikes against Syrian government targets. Air strikes would “break the will of pro-Assad forces,” Lieberman states confidently, and “result in a much sooner end to this terrible waste of life.” Despite the humanitarian rhetoric, such measures would entangle the United States in a very murky, dangerous conflict.

Their objectives are equally worrisome with regard to Iran. One gauge of the shrill, hawkish quality of congressional sentiment is a U.S. Senate resolution, which has some 32 co-sponsors, that urges the administration not even to consider deterrence and containment as a response if Tehran acquires a nuclear-weapons capability. Graham argues that containing Iran is simply not an option. “We’re not going to contain people like that, we’re going to stop them,” he stated at a press conference unveiling the resolution. In addition to pressuring the White House, both houses of Congress have passed a series of increasingly drastic economic sanctions against Iran, measures that only ratchet up tensions and strengthen the hand of hardliners in the Islamic Republic itself.

Advocates of a prudent foreign policy like to think that a vigorous congressional role in foreign policy—even beyond the constitutional requirement that war be declared by Congress—is an important restraint on chief executives who are inclined to embrace aggression. That may be true more often than not. But there are times, such as this one, when the sentiment for aggression is even stronger on Capitol Hill than it is in the White House. Both branches need to be watched carefully.

Ted Galen Carpenter, a senior fellow at the Cato Institute, is the author of eight books on international affairs, including Smart Power: Toward a Prudent Foreign Policy for America.