U.S. and Western military officials are calling on Iran to help stabilize Afghanistan, but historic tensions and allegations of arming militants raise doubts about Tehran’s intent.

U.S. foreign policy is largely directed by presidents, but Congress does have considerable influence, as this CFR Backgrounder explains.

International actors are redoubling efforts to restore Afghanistan’s agriculture sector and weaken the massive opium trade that helps fund the Taliban. But competing strategies and corruption could s…