Afghanistan is in a rough neighborhood. It might work out well for the US to let Afghanistan’s neighbors worry about it. From Doug Bandow at aeir.org:

Washington’s tragic misadventure in Afghanistan is over. Despite the botched ending, America’s withdrawal was long overdue. Central Asia never warranted so much U.S. attention.
Afghanistan first drew Washington in after the Soviets invaded. Few Americans knew where the country was. None expressed an interest in building a modern nation there. The idea was simple: arm Afghans to kill Moscow’s soldiers, thereby weakening what President Ronald Reagan accurately called the Evil Empire. Spread democracy and equal rights for women? Not so much.
A decade later the U.S.S.R.’s legions fled back into the Soviet Union. A couple years after that the Soviet-supported state collapsed, which was followed by a civil war among the victorious Mujahedeen. Washington had poured torrents of cash into Afghanistan, but foolishly allowed Pakistan to dole it out. This empowered radical jihadists, including Osama bin Laden, founder of al-Qaeda, Jalaluddin Haqqani, founder of the anti-Western Haqqani Network, and Gulbuddin Hekmatyar, founder of the radical Islamist Hezb-e-Islami, theParty of Islam. Some Americans complained that Washington didn’t stick around to “help” the Afghans. Had it done so, Americans would have been treated like Russians—shot at on their way out.
In 1994 a group called the Taliban arose. It enforced a 7th century fundamentalist interpretation of Islam. By 1996, it won control of most of the country by suppressing the Mujahedeen, and ending the chaotic violence which enveloped the country. The Taliban looked inward.