President Biden was proud to have overseen the end of America’s longest war in Afghanistan during his administration. This despite the chaotic and deadly withdrawal, and despite the fact that it had been former President Donald Trump who set the withdrawal in motion during his first term. But to finally bring this long chapter of U.S. foreign policy to an end, both presidents have unfinished business to attend to. First, in our chaotic withdrawal from Afghanistan, we abandoned tens of thousands of Afghan partners, people who loyally stood arm-in-arm with us throughout the conflict. Since then, they and their families have been systematically hunted, tortured, and killed by the Taliban; their crime was honorable service alongside U.S. troops in the hopes of a more hopeful and free future for Afghanistan. We made a sacred promise that we would not leave them behind. We failed to keep it, thus creating significant moral injury to our U.S. military veterans and damaged our international standing. Second, the withdrawal from Afghanistan deprived us of invaluable on-the-ground assets to gather intelligence about terrorist plotting from Afghanistan. While Biden officials have touted “over-the-horizon” intelligence and military capabilities, there simply is no substitute for assets and relationships in the country.  As a result, we are now less able to assess and deal with terrorist plotting that occurs unimpeded under Taliban rule. Indeed, since the withdrawal in 2021, Afghanistan has once again become a safe haven for terrorist organizations. According to a congressional investigation, “al Qaeda has set up eight new training camps in Afghanistan, propped up madrasas throughout the country, and established a new base to stockpile weapons.” Finally, the detention facility at Guantanamo Bay remains a potent example of U.S. hegemony and double standards. Thirty detainees remain, languishing since their capture nearly a quarter century ago. It is time to shutter Guantanamo once and for all. These stains on our security, values, and international standing urgently need to be addressed, and Presidents Biden and Trump can each do their part. First, Trump could “fix what Biden broke” (to borrow from the campaign slogan), and honor our commitment to our Afghan partners. These Afghans bravely served alongside our servicemembers and we left them behind. Trump should renew efforts to rescue them and support bipartisan legislation providing permanent residency for the previously rescued Afghans who remain in legal limbo inside the U.S.  Both Rep. Mike Waltz (R-Fla.) and Sen. Marco Rubio (R-Fla.) — Trump’s picks for national security advisor and secretary of State, respectively — criticized President Biden for leaving our Afghan partners behind, so both should be poised to help right what they are on record as seeing as a grievous wrong. Trump can take the win. Second, to make good on his campaign pledge to reassert American strength on the global stage, Trump should task his incoming national security team to evaluate the current state of threats to U.S. interests emanating from Afghanistan, including whether we have adequate resources in place to address them.  While Trump will take office facing multiple foreign policy challenges, he must not ignore terrorist threats that are reconstituting from within Afghanistan. Failure to take seriously the growing terrorist threat today will set the stage for the calamitous attacks of tomorrow. Finally, as one of his final acts as President, Biden should turbocharge efforts to transfer from Guantanamo those detainees who can be safely resettled to other countries.  The Biden administration reportedly scuttled a planned transfer of 11 Yemenis to Oman after the Hamas attacks on Israel on Oct. 7, 2023. A renewed effort to transfer them — along with any other detainees who can be safely transferred — should be a top priority. By doing so, Biden will be leaving Trump with fewer than 20 detainees at Guantanamo, and momentum to potentially complete the job of closing the facility once and for all.  Trump, potentially motivated by the exorbitant cost of detaining the aging detainee population (estimated at nearly $13 million per detainee each year) and eager to end this remaining vestige of our war in Afghanistan, could take decisive steps to close the facility for good. Again, Trump can take the win and brag about doing what Presidents Bush, Obama and Biden could not. Rescuing our Afghan partners will fulfill our sacred promise, taking seriously the terrorist threats from Afghanistan will keep us safe, and closing Guantanamo will end a shameful chapter. Those steps would constitute measurable foreign policy wins that finally put an end to the story of U.S. involvement in Afghanistan. As power transfers in Washington, these are steps that both Presidents can and should take.  Daniel J. Rosenthal is a fellow with the National Security Institute at the Antonin Scalia Law School at George Mason University and previously served as director for Counterterrorism at the National Security Council in the Obama White House and as senior counsel to the Assistant Attorney General for National Security at the Department of Justice.