The Taliban's rapid takeover of Afghanistan doesn't seem to have the Islamic Republic of Iran overly concerned. Iran and the Taliban have long had basic differences over their interpretations of Islam, in which the Sunni Taliban's radical Salafist beliefs continue to view Shiites unfavorably. Meanwhile, Iran is the main force that represents Shia Muslims in the Islamic world.

Perhaps it was these stark differences that resulted in the Taliban's August 8, 1998, attack on the Iranian consulate in Mazar-i-Sharif that killed eight Iranian diplomats. The killing came as such a shock to Iran that it nearly pushed it to declare war against Afghanistan and the Taliban. However, according to Hossein Mousavian, then the chairman of the Foreign Policy Committee of the Supreme National Security Council (SNSC), Supreme Leader Ali Khamenei vetoed the SNSC's decision to invade Afghanistan at the last minute.

Under such circumstances, Iran would definitely welcome the U.S. invasion of Afghanistan. Without any Iranian boots on the ground, one of Tehran's regional enemies had been toppled, removing a challenge to Iranian national security.