Twenty years ago today, nearly every American understood that the country would soon be going to war. But few could have guessed how this war would evolve or that it would last for so long.
While the Constitution divides war powers between Congress and the president, since World War II presidents have been increasingly in charge. Reviewing foreign policy since 9/11, it might seem that any inter-branch struggle is over, and Congress has irretrievably lost.
But it’s not that simple. Research finds that public opinion — which both shapes and is shaped by Congress’s reactions — can constrain what presidents want to do.
Congress’s struggle to regain power
Shortly after 9/11, Congress granted President George W. Bush broad authorizations to wage wars in both Afghanistan and Iraq. However, as these wars dragged on, Congress tried to claw back some of its war power. In 2007, Congress tried but failed to use its funding powers to mandate a timetable for withdrawal from Iraq. In 2011, lawmakers tried and failed to use the War Powers Resolution — a law enacted to rein in President Richard M. Nixon’s use of military power — to curb the Obama administration’s air campaign to protect civilians threatened by Moammar Gadaffi’s forces and intervene in Libya’s civil war. And periodically, over the past 20 years, members of Congress have proposed institutional reforms to curb the president’s use of military power. Those never gain traction.
These failings suggest that most legislators feel they have little to gain from seeking to lead in foreign policy. Instead, they watch how events unfold, supporting the president when things go well and criticizing when they do not. And that can be more effective than it sounds.
Public opinion matters
When members of Congress criticize foreign policy, they can arouse public pressure and push the White House to change course. Moreover, presidents who anticipate congressional backlash may moderate their policy choices, even knowing that Congress may not mandate a shift in policy. We can see both these dynamics over the last 20 years. The result is that presidents, even post-9/11, are far less imperial than many suppose.
Consider Congress’s failed effort to force Bush to set a timetable for withdrawal from Iraq after Democrats regained control of both the House and Senate in the 2006 midterms. While the legislative assault failed, Congress increased its criticism of the war and launched investigations into its conduct. This made it hard for Bush to rally public support for the war. Ultimately, this political pressure made it easier, in 2008, for the incoming Obama administration to reduce the U.S. presence.
Domestic politics also influenced President Barack Obama’s decisions in Afghanistan early in his first term. Obama followed his commanders’ advice to escalate in Afghanistan with a surge of tens of thousands of troops. But given softening public support and criticism from prominent congressional Democrats, he simultaneously announced a time frame for their withdrawal.
Doing so made little military sense, undercutting the surge’s logic as a counterinsurgency strategy.
But it made political sense. Obama was trying to navigate between hawks demanding bold action and doves demanding a pullback. The move also shows the administration knew that U.S. public opinion was unlikely to support large troop deployments indefinitely.
Public opinion can change the shape of war
Knowing that approval for putting American lives at risk had faded a decade since 9/11, the Obama administration crafted an Afghanistan strategy that increasingly relied on drone strikes and other actions that minimized the war’s costs and political visibility. President Donald Trump largely continued this. The policy didn’t defeat the Taliban, but it avoided an embarrassing defeat, insulated both administrations from criticism, and kept the U.S.’s longest war beneath the public radar for years.
Presidents know that public support is critical. In 2013, the Syrian government used chemical weapons on its citizens, which Obama had declared to be a “red line” that would trigger U.S. involvement in the civil war. The president declared that it was in the United States’ national security interests to take action. But — despite years in which presidents had acted alone — he announced he would first seek congressional authorization, explaining, “All of us should be accountable as we move forward, and that can only be accomplished with a vote.” Otherwise “Congress will sit on the sidelines and snipe. If it works, the sniping will be a bit less; if it doesn’t, a little more.”
Here Obama revealed, in so many words, that Congress’s “sniping” did indeed influence presidential decision-making about war and peace. It could erode public support and raise the political costs of military action.
That restraint did not reduce congressional criticism. Many lawmakers blasted Obama for “leading from behind” in Libya’s civil war. Leading Democrats and Republicans alike chastised Trump’s abrupt 2019 decision to withdraw U.S. troops from northern Syria for betraying Kurdish allies. And Trump even reversed himself sending some troops back, ostensibly to protect Syrian oil fields. But these presidents knew that they risked still more costly losses of public support if they had instead escalated U.S. military involvement and failed to achieve their objectives speedily.
Ending forever wars
In 2016, Donald Trump ran for president blasting his predecessors’ “forever wars.” He won significant support in areas that had suffered disproportionately high casualty rates in Iraq and Afghanistan. Trump’s 2020 deal with the Taliban to withdraw all remaining U.S. troops fulfilled a vague campaign pledge and was broadly popular.
In completing that withdrawal, Biden also aligned policy with public opinion. Afghanistan’s shockingly swift fall to the Taliban and the chaotic scenes from Kabul that dominated Western media for weeks brought tremendous criticism from across the political spectrum, hurting the administration politically. And yet most Americans still support the decision to withdraw, even if they object to the decision’s execution. Congressional objections to continuing the 9/11 wars — and the public opinion that those objections both channeled and amplified — won in the end.
Douglas L. Kriner is the Clinton Rossiter Professor in American Institutions at Cornell University. He is co-author (with Dino Christenson) of The Myth of the Imperial Presidency: How Public Opinion Checks the Unilateral Executive (University of Chicago Press, 2021).