Syrian President Bashar Assad’s recent use of chemical weapons against his own people is a grim reminder of the deep challenges that continue to exist in Syria and the surrounding region.

Compounding the problem is the brutal and ongoing presence of the Islamic State, also known as ISIS, which has taken a toll in recent months but remains far from defeated.

It’s no wonder that many experts consider this the most complicated geopolitical challenge in recent history.

The involvement of Russia, Iran, Turkey, and other groups in Syria combined with an unprecedented refugee crisis have led to a fractured situation that may take decades to fully resolve.

While the situation on the ground is complicated, it is refreshing to have a president who is ready and willing to take decisive action when necessary.

The most powerful currency that we have—our credibility with our international counterparts—was sacrificed during the Obama presidency in order to preserve President Barack Obama’s misguided nuclear deal with Iran.

Obama’s lack of follow through in 2013, when the Assad regime launched a separate chemical attack that killed over 1,000 innocent Syrians, created a crisis of trust. The Syrian regime crossed the “red line” that Obama himself created, but there were no repercussions.

In contrast, President Donald Trump sent a clear message that he is willing and ready to respond when necessary by acting decisively in response to Assad’s most recent use of chemical weapons.

The Trump administration deserves credit for its measured response to Assad and its bold approach to ISIS. But the significance and complexity of the regional threat, particularly from ISIS, requires renewed attention from Congress.

>>> Where the Fight Against ISIS Stands, and How the US Can Win

At this critical moment, it is vital that the United States has a comprehensive strategy that addresses the situation in Syria. Part of this strategy should include Congress passing a new Authorization for Use of Military Force (AUMF).

The Congress is the body our Constitution entrusts with the ability to declare war. This power was further solidified by the War Powers Resolution that was passed in the wake of the Vietnam War, as Congress is the body closest to the American people and the most accountable to the citizenry for its decisions.

Last month, I introduced a revised AUMF specifically aimed at defeating ISIS in Iraq and Syria.

The AUMFs Congress passed in 2001 and 2002 in response to the attacks of Sept. 11, 2001, have served a critical purpose, but their usefulness has been exhausted as the once-dominant al-Qaeda threat has given way to ISIS.

Some argue that al-Qaeda evolved into ISIS, and therefore the old AUMFs are still valid for today’s fight. Others argue that ISIS falls under the “associated forces” provisions of old AUMFs.

While these arguments may have merit, their critical assumptions have not been tested in court, and relying on them in the fight against ISIS would put our armed forces on a tenuous legal footing.

>>> Read The Heritage Foundation’s analysis of the 2001 AUMF and the need for a new AUMF targeting ISIS.

Our military forces need certainty in their mission and in their legal mandate. It is a much wiser course of action to take up this new AUMF to provide undisputed clarity to our troops and to ensure that our nation is on strong legal footing.

Furthermore, over 75 percent of my colleagues in both the House of Representatives and the Senate have never cast a vote to authorize our current wars in Iraq, Syria, and Afghanistan, and their voices must be heard on our next steps in this region.

The costs of both action and inaction in Syria are great. If the U.S. is to defeat ISIS and restore stability to a fragile region, it is critical that the American people’s elected representatives in Congress debate and vote on a new AUMF.

I commend the president for his decisive leadership in confronting all threats to American interests in Syria, both from ISIS and the Assad regime.

He has operated in line with his Article II powers as the commander in chief of our armed forces, but it is crucial that Congress now contribute to the conversation and give our military the tools to succeed.

This AUMF will do just that. It authorizes and fully supports the mission of our brave men and women, and it is time for Congress to take it up.