On July 2, the U.S. military handed control of the vast Bagram Air Base to the Afghan government. U.S. troops and their NATO allies are now on track to leave Afghanistan by mid-July, well ahead of U.S. President Joe Biden’s Sept. 11, 2021, withdrawal deadline.

According to a new analysis by researchers at Brown University, America’s two-decade war in Afghanistan cost it nearly $2.3 trillion. Now, Afghanistan’s neighbors — Pakistan, Iran, China, India and the Central Asian countries — are wondering just how much it will cost them to maintain security after the United States is gone.

In late June, the U.S. intelligence community concluded that the Afghan government could collapse within six months of the U.S. withdrawal — a stark downward revision of its earlier, more optimistic assessment. As the Taliban has swept through northern Afghanistan, capturing dozens of districts and major cities, Afghan security forces have often surrendered without a fight.