Last week marked the end of our mission in Afghanistan and America’s longest war. Our nation owes the men and women who served a debt that can never be repaid. They carried out their mission with bravery, dedication and distinction. They and their families also bore the brunt of a 20-year war whose objectives our political leaders failed to define.

What began as a limited campaign to deny Al Qaeda safe haven grew into a futile nation-building effort. It has long been clear that America could neither resolve Afghanistan’s civil war nor stand up its civilian government at the point of a gun. After 20 years, two trillion dollars, the loss of over 2,400 American troops and nearly 21,000 wounded (and many more with invisible wounds of war), 1,100 allied service members, 47,000 Afghan civilians and 66,000 members of the Afghan military and police, it was past time to conclude our mission. In the months ahead, we have the obligation to assess what happened over the past 20 days and the past 20 years, but President Joe Biden was right to end America’s longest war.

Our work to protect the American people, here and abroad, will continue. The terrorists who killed 13 of our soldiers and dozens of Afghan civilians at the Kabul Airport must be brought to justice. We must make every effort to finish the evacuation of any remaining Americans wishing to come home and of our Afghan partners. We also must protect against continuing terrorist threats from ISIS-K and others, and support U.S. personnel in the diplomatic, military and intelligence work that lies ahead.

The end of this war demands our responsibility to learn from it. As a member of the Senate Intelligence Committee, I will ask hard questions about what we could have done to better plan for the fall of Kabul and swiftly evacuate our citizens, allies and Afghan partners. Just as important, perhaps even more so, the Senate must undertake a sober and thorough examination of the serial misjudgments across multiple administrations that brought us to this point. That is the least we owe every American after two decades of war — and especially the men and women who served bravely on its front lines.

Michael Bennet is a U.S. senator for Colorado.