Editor’s Note: TNI’s January/February 2017 print issue convened a symposium on the most significant national-security challenge awaiting the Trump administration. You can find all entries in the series here.

THE GREATEST security challenge facing the next president is the national debt. The United States owes nearly $20 trillion, not counting the nearly $50 trillion entitlement debt. The time approaches when America will no longer be able to manage its debt and fund national defense.

The debt continues to explode because Congress ignores the limitations of the Constitution. The federal government was intended to be limited to specific, enumerated powers, and yet, today’s federal government reaches its meddling hand far afield from the Founders’ intent. To minimize new debt and manage existing debt, officials will have to resurrect the separation-of-powers doctrine. Only by separating power from the president will spending be contained. Power that is not constitutionally given to the president should be taken back by Congress, the states and, ultimately, the people.

The greatest and most ominous of government’s power is the ability to go to war. The Founders extensively debated and then concluded that on issues of war, Congress would be required to give its authority. Neoconservatives and their disciples, elected and academic, feel the constitutional requirement for Congress to declare war is no longer applicable. Under President Obama’s tenure, the United States has gone to war in Libya, Syria and Iraq, and engaged in military activities in Yemen without congressional authority. In each instance, the case can be made that unilateral presidential intervention led to less stability, and less security for the United States.

Military interventions are expensive. The money the United States spends on interventions could otherwise be used for weapons of deterrence or upkeep of its decaying nuclear arsenal.

Restoring the constitutional mandate that war needs to be authorized by Congress would go a long way to ensuring that a full-throated debate occurs before troops are placed in harm’s way.

The Trump administration can take the lead here, but nothing prevents Congress from engaging in what is maybe its most important constitutional role: war authorization. Congress should be resolute and either pass an appropriate authorization or disapproval for current U.S. interventions while simultaneously repealing the 2001 and 2002 Authorization for Use of Military Force.

The ease with which Congress allows the president to engage in several “hotspots” around the world tends to make these regions less safe. Members don’t want to appear soft on terrorism or unsupportive of the military. It is easier for them to politicize the ineptitude of an administration’s strategy than to exert proper oversight.

Time after time, the United States has intervened around the world without congressional approval. In Libya, the overthrow of Muammar el-Qaddafi resulted in chaos, leaving an inept Libyan government and large swathes of territory under ISIS control.

Yemen is another engagement in which Congress has had little to no input. The military and advisory support given to Saudi Arabia fosters future jihadists that want to destroy America. The United States is providing air refueling support; intelligence, surveillance and reconnaissance; and U.S. military hardware to Riyadh. In the summer of 2016, a fifteen-year-old boy was killed by a U.S. cluster bomb. In October, Saudi forces repeatedly bombed a funeral in Yemen, in which 140 people were killed and as many as five hundred injured.

The Yemeni crisis has been going on for almost two years with no signs of abatement. Houthi rebels have already tried to attack the United States by launching two separate missile attacks on the USS Mason. Let’s not forget the USS Cole bombing, which also occurred in Yemen. Another unfortunate attack on a U.S. vessel or other American personnel will predictably incite calls for more intervention. Lawmakers must see the writing on the wall. When a president sends U.S. troops on an operation not supported by Congress, often America becomes stuck in a stalemate. War without congressional debate seems to be a recipe for war without rhyme, reason or any concept of victory.

In September, a few members and I attempted to insert congressional prerogative in matters of national security. Congress took a vote on stopping the sale of 153 Abrams tanks to Saudi Arabia. Over seventy senators voted to allow the sale. Ironically, these same senators voted overwhelmingly, the same day, to allow 9/11 victims to sue the Saudi government for its possible role in the 2001 bombings. Although we lost the vote in the Senate, President Obama eventually decided to suspend the sale of U.S. air-dropped munitions. In this instance, loud voices in Congress did change a foreign-policy outcome.

The implications of not adhering to constitutionally established roles have huge consequences for U.S. foreign policy. Strategic, operational and tactical considerations by a president and military leaders are of immense consequence. All of these powers are derived from the Constitution. If the Constitution isn’t adhered to as the Founding Fathers intended, the nation and American credibility abroad suffer.

Rand Paul is a U.S. senator from Kentucky.

Image: Air strike in Sanaa. Wikimedia Commons/Creative Commons/Ibrahem Qasim