On 11 September 2001, the world witnessed a terrible attack against our nation that took thousands of lives and changed millions more lives forever. The events of that day fundamentally changed the way we view American national security. But the decision to plunge the US into a state of perpetual war was taken rashly, without the debate that such a momentous decision demanded.

Twenty years on, the US and the world are much worse off for this failure of leadership. It is time to turn the page on two decades of endless war with a vague and ever-shifting mission. While this begins with removing the 2001 and 2002 authorizations for use of military force from the law books, it will also require decisive changes in our foreign policy decision processes and resource allocation.

Shortly after the attacks, President Bush sent a 60-word blank check to Congress that would give him or any other president the authority to wage war against enemies of their choosing. It was a sweeping resolution known as the 2001 authorization for use of military force, or the 2001 AUMF. I was the lone vote in Congress against the authorization because I feared it was too broad, giving the president the open-ended power to use military force anywhere, against anyone.

The human cost has been high: an untold number of civilian casualties overseas, two generations of American soldiers sent to fight without any clear objective or oversight and thousands of our troops and other personnel killed, wounded and traumatized in action.

The Afghanistan war alone has cost more than $2.6tn taxpayer dollars and killed more than 238,000 individuals. The 2002 AUMF, which authorized war against Iraq based on fabricated claims of weapons of mass destruction, has cost $1.9tn and killed an estimated 288,000. Together, these two AUMFs have been used by three successive presidents to engage in war in at least seven countries – from Yemen to Libya to Niger – against a continually growing list of adversaries that Congress never foresaw or intended. The Bush, Obama and Trump administrations have further identified to Congress combat-ready counter-terrorism deployments to at least 14 additional countries, indicating that the AUMFs could justify armed combat in those places as well. Only 56 current members of the House and 16 senators were present at the 2001 vote, making a mockery of the constitutional principle that only the people’s elected representatives in Congress can send our country to war.

The results today are a perpetual state of war and an ever-expanding military-industrial complex that consumes a greater and greater amount of our resources every year. Pentagon spending since 9/11 (adjusted for inflation) has increased by almost 50%. Each hour, taxpayers are paying $32m for the total cost of wars since 2001, and these wars have not made Americans safer or brought democracy or stability to the Middle East. To the contrary, they have further destabilized the region and show no sign of ending or achieving any of the long-ago stated goals.

Additionally, many of these actions were essentially hidden from the American people by using funds from an account meant for unanticipated developments called overseas contingency operations. Congress appropriated nearly $1.9tn for this account, enabling continuing military actions and wars in several countries, exempted from congressional budget rules. Thankfully, President Biden ended this budget practice this year. But two decades of reliance on emergency and contingency funding sources has resulted in less oversight, less transparency and higher levels of waste.

It’s time we end these forever wars. With a coalition of partners, allies and advocates both inside the halls of Congress and out, we are finally on the cusp of turning the page on this state of perpetual war-making.

To begin with, I worked with colleagues on a bipartisan basis to urge President Biden to withdraw troops from Afghanistan swiftly and efficiently. He heeded our calls and undertook an evacuation operation unprecedented in its scale, while keeping our commitment to withdraw military occupation before 11 September. The ill-defined AUMF allowed the Afghanistan war to drag on for two decades, even after we had achieved the ostensible mission of eliminating the threat posed by al-Qaida to the United States. The challenges of our evacuation, and the fact that the Taliban could regain control of Afghanistan despite our 20-year war, merely underscore why Congress should not authorize open-ended military engagements.

For that very reason, it’s not enough just to withdraw our forces. We must rein in executive power and keep it from being abused by any more administrations – Democratic or Republican. In my role on the Democratic platform drafting committee, I successfully advocated for including a repeal of the 2001 and 2002 AUMFs in the Democratic party platform. In a historic 268–161 vote, the House passed my legislation to repeal the 2002 AUMF in June, and the Senate foreign relations committee voted 14-8 in August to do the same, with both votes drawing bipartisan support. I am also calling on Congress to address the outdated 2001 AUMF. Any new authorization for use of military force must include safeguards to protect against overreach – including a clear and specifically defined mission objective, reporting requirements to increase transparency and accountability and a sunset clause or timeline within which Congress should revisit the authority – among other provisions.

Congress must reclaim its constitutional duty to oversee matters of war and peace. In addition to repealing these AUMFs, we also need to revisit the broader statutes that govern war powers so that Congress can more effectively rein in presidential war-making – a project being pursued in earnest by my colleagues, Representatives Jim McGovern (D-MA) and Gregory Meeks (D-NY). But we need to go beyond just changing the law. We need to change our approach to the world, away from framing every challenge as one that requires military force as a response. When we use the frame of war to analyze the challenge of terrorism, we artificially limit the solutions available to us, crowding out the political and diplomatic approaches that offer the only real durable solutions for US security.

Helping to build an equitable world that values inclusion and human rights won’t make terrorism disappear. But it would dramatically shrink the space for terrorist groups to operate and weaken the real grievances that they exploit. Not only that, but a US foreign policy based on supporting development and human rights would allow us to pursue a proactive strategy in line with progressive values, rather than one where America finds itself constantly in a militarized defensive crouch.

A new foreign policy approach requires a significant reallocation of our resources to address the very real and immediate threats we face. The world is still confronting a global pandemic. Hundreds of millions of people are living in extreme poverty, with many more pushed out of the middle class by Covid-19. And the climate crisis looms over us, threatening every gain in human progress we have made over recent decades. It is unacceptable to continue to pour billions of dollars into the Pentagon when the real challenges we face require diplomatic and development solutions.

A new and better approach also requires empowering our civilian foreign policy agencies to set the agenda. For too many years, we have outsourced our foreign policy to the Pentagon. The overwhelming human and financial resources that the Pentagon brings to foreign policy decision-making too often push diplomatic or development concerns to the background. Rebalancing the emphasis of our foreign policy will give us the opportunity to explore solutions that could be both more humane and more durable.

The president has a role in fixing the errors of the past 20 years. But ultimately Congress must step up. For two decades, Congress has failed to exercise its constitutionally mandated role to conduct proper oversight, to make appropriate decisions about budgets and resource allocation, and – most importantly – to play the singular role the constitution assigns to us of making decisions about war and peace. The American people have made clear their preference for moving beyond endless war. Congress needs to hear their voice and act.

• Congresswoman Barbara Lee is a member of the House appropriations committee, chair of the subcommittee on state and foreign operations, and co-chair of the House steering & policy committee. As a member of the House Democratic leadership, she is the highest-ranking Black woman in the US Congress

• This essay is co-published with the Brennan Center for Justice at NYU School of Law as part of a series exploring new approaches to national security 20 years after 9/11