There is nothing in Iran and Taliban’s past relationship, which leads one to believe that these two sides can cooperate. Taliban’s hardcore theology includes anti-Shiite prejudice that often bought it to the brink of war with Iran during its days in power. On August 8th 1998, Taliban killed eleven Iranian diplomats and carried out a massacre against the Hazaras, an ethnic shi’ite minority in Afghanistan. By September 1998, the relation between the two countries was bad enough for Iran to send 70,000 troops to border with Afghanistan to carry out war games. After Taliban send 30,000 troops to border, Iran responded by sending an additional 130,000 troops to conduct war games on the border. Given Iran’s tumultuous relationship with Taliban, it is hard to fathom that the Iranian government will ever want Taliban back.
Yet the U.S. Intelligence is accusing Iran of providing weapons to Taliban. This CFR backgrounder, Iran and the Future of Afghanistan, provides some explanation as to why Iran could support Taliban:
Peter Tomsen, former U.S. ambassador to Afghanistan, told CFR.org in 2006 that a weakened Afghan state lessens the likelihood it can become a U.S. ally against Iran. By maintaining a certain level of instability, he said, “it keeps us tied down. After all, we have air bases in Afghanistan where we could mount attacks on Iran.” Some analysts call it “managed chaos,” a strategy they say is similar to the one Iran employs in Iraq. Others see abetting the Taliban as a means to boost Iran’s leverage at a time when it is under pressure to end its uranium-enrichment program. Despite Iran’s Shiite brand of Islam, Tehran has thrown its support behind majority Sunni groups in Iraq and elsewhere. As Takeyh writes in his book, “[F]or Tehran the issue in Afghanistan has not been ideological conformity but stability.”
Though there is a possibility that the Iranian government is not directly involved. As the CFR backgrounder states:
Some experts (…) say the weapons could have been smuggled into Afghanistan via various third-party channels. Others suggest they are being supplied by hard-line components within the Iranian Revolutionary Guards (the Mashhad-based Fourth Corps is responsible for projecting Iranian power in Afghanistan), which has a separate agenda from the Iranian foreign ministry, which in turn has a separate agenda from Iran’s business community. “We’re talking about rogue elements,” Col. Christopher Langton, a senior fellow at the London-based International Institute for Strategic Studies, told CFR.org in 2006, “maybe even cross-border organizational criminal groupings.” He said that arms factories in Pakistan’s North West Frontier Province make copies of the weapons made in Iran.
In order to pursue their regional interests, there have been some strange partnerships in the international realm (most notably KDP’s alliance with Saddam Hussein in 1996) and maybe this is one of them.