In his first public hearing on Capitol Hill since he became secretary of Defense in January, James Mattis made an unusual proclamation: It’s time for the United States to go to war.

“I would take no issue with the Congress stepping forward with an AUMF,” Mattis told the Senate Defense Appropriations Subcommittee on March 22. AUMF, in this case, refers to an Authorization for Use of Military Force — legislation passed by Congress to empower the U.S. military to hunt down and eliminate a specific target or organization.

“I think it’d be a statement of the American people’s resolve,” he said. “The elected commander-in-chief, both the last administration and the current administration, I think, have a duty to protect the American people, and what we stand for, from this enemy.”

Secretary of Defense Jim Mattis meets with Qatar’s Minister of Defense Khalid bin Mohammad Al Attiyah at the Pentagon in Washington, D.C., March 27, 2017.Photo by DoD
Secretary of Defense Jim Mattis meets with Qatar’s Minister of Defense Khalid bin Mohammad Al Attiyah at the Pentagon in Washington, D.C., March 27, 2017.

Mattis’ comments may seem odd to even the most casual observer of American foreign policy: The military has been leading a multinational coalition against ISIS since 2014, when President Barack Obama authorized airstrikes against the terror group’s strongholds in Syria. Between those operations and the wars in Iraq and Afghanistan, the United States has engaged in nearly 16 years of continuous armed conflict in the Middle East and Southwest Asia, longer than the United States’ official involvement in Vietnam.

Why are we technically “not at war”?

When it comes to how the United States goes to war, the Constitution is somewhat ambiguous. Article II vests the executive branch with the power to wage war with the president as commander-in-chief, but the power to actually declare war, as well as raise, organize, and actually deploy troops, lies with Congress. The president can take immediate action in the face of an imminent threat like a Pearl Harbor or 9/11, but only Congress can mobilize the U.S. military for a prolonged, bloody conflict. Up through World War II, Congress was happy to formally declare war against foreign powers, as it did on Great Britain in 1812, Mexico in 1846, Spain in 1898, Germany and Austria-Hungary in 1917 at the outset of World War I, and the Axis powers in 1941.

Even though United States hasn’t formally declared war since the country sacked up to beat back fascism in World War II, American troops are ubiquitous worldwide, engaged in protracted battles with the many-headed hydra of global terror networks. There are more than 6,000 U.S. troops in Iraq, at least 600 in Syria, and 8,400 in Afghanistan who continues to bolster local forces in their struggle to beat back the rising tide of ISIS and the remnants of the Taliban in Afghanistan. In the last month, the Pentagon members of the deployed the 75th Ranger Regiment and the 11th Marine Expeditionary Unit, howitzers in tow, to Syria while local security forces launched an assault on the ISIS capital of Raqqa. In recent weeks, U.S. officials have also pledged to send more troops to take on the terror cult in the northern Iraqi city of Mosul.

What does the AUMF actually do?

The campaigns waged by American troops against ISIS, and the broader War on Terror, derive their legitimacy from the first AUMF in 2001 — a call to arms passed by Congress three days after Sept. 11 that authorized the U.S. military to hunt down those responsible for the attacks on the World Trade Center and Pentagon.

U.S. Army Pfc. Derick Zamudio, a cavalry scout assigned to the 1st Squadron, 73rd Cavalry Regiment, 2nd Brigade Combat Team, 82nd Airborne Division, scans his sector during his guard shift near Makhmour, Iraq on Jan. 27, 2017.Photo by DoD
U.S. Army Pfc. Derick Zamudio, a cavalry scout assigned to the 1st Squadron, 73rd Cavalry Regiment, 2nd Brigade Combat Team, 82nd Airborne Division, scans his sector during his guard shift near Makhmour, Iraq on January 27, 2017.

The 2001 AUMF has two important clauses. The first empowers the president to “use all necessary and appropriate force against those nations, organizations, or persons he determines planned, authorized, committed, or aided the [9/11 terror attacks],” a clear mandate to then-President George W. Bush to, in his words, “bring our enemies to justice or bring justice to our enemies.”

The second clause also empowers the executive branch to use that “necessary and appropriate force” to “prevent any future acts of international terrorism against the United States by such nations, organizations or persons” — a call to the president to take the fight to terrorists wherever they may be. In the past, America went to war against nation states; under the terms of the AUMF, the country is at war with terrorists, wherever they may be or whatever they may have done.

So what’s the problem?

Authorizing conventional troops without a formal declaration of war isn’t new to the post-9/11 era. Since the end of World War II, presidents have attempted to justify military action under everything but a formal declaration of war. President Harry Truman called U.S. involvement in Korea a “police action,” while President Lyndon Johnson used Congress’ Gulf of Tonkin Resolution to check “communist aggression” in Vietnam with conventional troops. A decade later, as the the Vietnam War wound down, Congress crafted the War Powers Resolution to reign in presidential generalship. It permitted war only in the event of a formal declaration, national emergency, or “specific statutory authorization,” like the Gulf of Tonkin Resolution — and the 2001 AUMF.

But neither Article I of the Constitution nor the War Powers Resolution explicitly specify what a congressional “declaration of war” actually looks like. Since 9/11, three successive presidents have interpreted the 2001 AUMF to provide congressional approval for combat without congressional oversight, a rubber stamp for the executive branch to wage war as it sees fit. Namely, the vague mandate that the president “prevent acts of international terrorism” in the AUMF’s second clause has been used as a blanket justification for numerous foreign military operations for almost 16 years.

Marines with Bravo Battery, 3rd Battalion, 11th Marine Regiment, reloads the M777 Lightweight 155mm howitzer during Integrated Training Exercise (ITX) 2-17, aboard Marine Corps Air Ground Combat Center, Twentynine Palms, California, February 11, 2017. Photo by DoD
Marines with Bravo Battery, 3rd Battalion, 11th Marine Regiment, reloads the M777 Lightweight 155mm howitzer during Integrated Training Exercise (ITX) 2-17, aboard Marine Corps Air Ground Combat Center, Twentynine Palms, California, February 11, 2017.

Most recently, this has applied to Operation Inherent Resolve, the U.S.-led campaign against the Islamic State in Iraq and Syria. Instead of returning to Congress to seek a new authorization for military force, the Obama administration claimed that the post-9/11 AUMF (and Congress’ 2002 Iraq War Resolution) provided all the legal basis he needed to bring the fight to ISIS. In December 2016, the outgoing Obama administration expanded on this claim, arguing that “the 2001 AUMF has authorized the use of force against the group now called ISIL since at least 2004” with a jumbly history of the group’s rise:

“The facts underlying this determination are as follows: a terrorist group founded by Abu Mu’sab al-Zarqawi — whose ties to Osama bin Laden dated from al-Zarqawi’s time in Afghanistan and Pakistan before the September 11th attacks — conducted a series of terrorist attacks in Iraq beginning in 2003. These attacks prompted bin Laden to ask al-Zarqawi to merge his group with al-Qa’ida. In 2004, al-Zarqawi publicly pledged his group’s allegiance to bin Laden, and bin Laden publicly endorsed al-Zarqawi as al-Qa’ida’s leader in Iraq. For years afterwards, al-Zarqawi’s group, which adopted the name al-Qa’ida in Iraq (AQI) when it merged with al-Qa’ida, conducted deadly terrorist attacks against U.S. and coalition forces. In response to these attacks, U.S. forces engaged in combat operations against the group from 2004 until U.S. and coalition forces left Iraq in 2011. The group has continued to plot attacks against U.S. persons and interests in Iraq and the region—including the brutal murder of kidnapped American citizens in Syria and threats to U.S. military personnel that are now present in Iraq at the invitation of the Iraqi Government.

The subsequent 2014 split between ISIL and current al-Qa’ida leadership does not remove ISIL from coverage under the 2001 AUMF.”

That’s a highly selective history, but it illustrates how a president doesn’t really need a war to send Americans into battle — he really just needs political window-dressing, some sort of symbolic nod from Congress like the AUMF. And a symbolic nod is not the same as accountability to the American people or their representatives. While polling shows the American public remains concerned about the threat of terrorism, the data suggests voters are also weary of prolonged conflicts like Iraq and Afghanistan, preferring airstrikes and the restrained use of special operators to the deployment of ground troops en masse. Yet, the lack of a formal, tailored war declaration means the American public has no real say in how, when, where, and for how long the country goes to war. Which, for years, most of Congress seemed quite comfortable with.

Why hasn’t Congress done anything about it?

In recent years, some lawmakers have sought to reassert Congress’s constitutional authority in the war-making process. In 2014, senators John McCain of Arizona and Tim Kaine of Virginia introduced a bipartisan bill to reform the War Powers Act and prevent presidents from unilaterally waging a prolonged military campaign. As the nature of war changes from nation to nation, the senators contended, the legal definition of war and how it’s declared needs to change, as well.

Chairman of the senate Armed Services Committee Sen. John McCain questions Secretary of Defense Ash Carter on the recently brokered Iran nuclear deal during testimony before the Senate Armed Services Committee in Washington, D.C., July 29, 2015. Carter was joined by Secretary of State John Kerry, Chairman of the Joint Chiefs of Staff Martin Dempsey and Energy Secretary Ernest Moniz.Photo by DoD
Chairman of the senate Armed Services Committee Sen. John McCain questions Secretary of Defense Ash Carter on the recently brokered Iran nuclear deal during testimony before the Senate Armed Services Committee in Washington, D.C., July 29, 2015. Carter was joined by Secretary of State John Kerry, Chairman of the Joint Chiefs of Staff Martin Dempsey and Energy Secretary Ernest Moniz.

“The Constitution gives the power to declare war to the Congress, but Congress has not formally declared war since June 1942, even though our nation has been involved in dozens of military actions of one scale or another since that time,” McCain said on the Senate floor after introducing the bill. “It is essential for the Congress and the president to work together to define a new war powers consultative arrangement that both reflects the nature of conflict in the 21st century and is in line with our Constitution.” The bill died in committee without getting a vote.

Despite its shortfalls, the AUMF remains the best legal mechanism for Congress to fulfill its constitutional role as a check on the presidency in the absence of a traditional total war. But actually passing an AUMF can be tricky business in a polarized Congress. Obama sent Congress a draft AUMF explicitly authorizing the new ISIS campaign in 2015, but the full House and Senate failed to even consider the legislation, let alone vote; CBS News reported at the time that while progressive lawmakers worried about handing a president a blank check as it did after 9/11, Republican lawmakers were reportedly concerned with handing Democrats a foreign policy victory on the verge of the 2016 presidential election. Their inaction in 2015 incentivized Obama and his future successors to simply rest on the 2001 AUMF as justification for new conflicts abroad; by butting heads on the specifics, lawmakers missed a chance to reign in the imperial executive.

Now what?

Despite ISIS’ threats to the United States, the new Congress is now debating the merits of another prolonged Middle East engagement — and considering a new, narrower AUMF. The Washington Post reports that lawmakers have introduced several legislative packages design to do everything from full repeal the 2001 AUMF to provide unrestrained authorization to only target al Qaeda, the Taliban and ISIS. Hence Defense Mattis’ recent comments in favor of a new AUMF. “[I] have not understood why the Congress hasn’t come forward with this, at least to debate,” he told the Senate Defense Appropriations Subcommittee in March.

Even if a new AUMF introduced some clarity to the latest American conflict, larger questions about U.S. war powers would remain unanswered. Presidents have hyperextended their military muscles for more than 150 years, starting with Abraham Lincoln’s suspension of habeas corpus during the Civil War. Few chief executives since World War II have held up military action while “waiting for Congress to baptize it with a name,” as Supreme Court Justice Robert Grier Once put it. With the American people balking at the prospect of a future burdened by perpetual war, it’s up to Congress to assert itself to protect, and defend, the Constitution.