The base was used by American forces following the attacks of Sept 11, 2001.

Archived version: https://archive.is/newest/https://www.straitstimes.com/world/united-states/trump-says-bad-things-will-happen-if-afghanistan-does-not-return-bagram-air-base

Disclaimer: The article linked is from a single source with a single perspective. Make sure to cross-check information against multiple sources to get a comprehensive view on the situation.