Shutting Out Iran Will Make the Afghan War Even Deadlier

Michael Kugelman/ Foreign Policy

ix months after the Trump administration withdrew from a multilateral nuclear deal with Tehran, triggering an initial reimposition of sanctions, Washington has reinstituted additional punitive measures on Iran. U.S. President Donald Trump described the latest sanctions, which went into effect on Nov. 5 and target the key Iranian industries of oil, banking, and shipping, as the “toughest ever.”

Washington’s ever-hardening line on Iran is a big mistake—and not just because it strains alliances with NATO, undermines global nonproliferation, and risks destabilizing the Middle East. Scuttling the nuclear deal and sanctioning Tehran could also cause America’s unending war in Afghanistan, Iran’s eastern neighbor, to escalate violently.

Washington has already telegraphed its concern about the Taliban’s ties to Tehran. Last month, the U.S. Treasury Department and six Persian Gulf nations sanctioned seven Taliban leaders and two officers with Iran’s Islamic Revolutionary Guard Corps. The stated goal is to “disrupt Taliban actors and their Iranian sponsors that seek to undermine the security of the Afghan government.” U.S. Treasury Secretary Steven Mnuchin described “Iran’s provision of military training, financing, and weapons to the Taliban” as “yet another example of Tehran’s blatant regional meddling and support for terrorism.”

But with no prospect of improving relations with the United States, at least as long as Trump remains president, Iran has a strong incentive to increase military support to the Taliban, a persistent thorn in America’s side. The Afghan Taliban are already a beneficiary of episodic Iranian military assistance, but this surge in support could come at the very moment when Washington is making a full-bore effort to bring the insurgents to the peace table.

Backing the Taliban is a relatively cost-free way to retaliate for the canceled deal, and the covert nature of this assistance gives Tehran plausible deniability. More funding would also bolster Iran’s influence over the Taliban—a useful hedging strategy if the United States leaves Afghanistan. Additionally, it strengthens the Taliban’s capacity to target the Afghanistan affiliate of the Islamic State—a group opposed by both Iran and the Taliban, and with which the latter regularly clashes violently.

At first glance, the idea of Iran-Taliban cooperation may seem strange. Iran is a Shiite state; the Taliban are Sunni militants. Tehran enjoys considerable influence among Afghanistan’s Shiite Muslims, who were often targeted for murder by the Taliban during the Afghan civil war in the 1990s. In 1998, after nine Iranian diplomats died in an attack on their consulate in the Afghan city of Mazar-e-Sharif, Iran mobilized 200,000 troops on its border with Afghanistan and nearly went to war with the Taliban, which ran the country at the time.

Tehran has also worked closely with the Afghan government in Kabul. At the 2001 Bonn Conference, which cobbled together Afghanistan’s first post-Taliban government, Iranian negotiators played an instrumental role in fashioning a final agreement. Iran and Afghanistan signed a strategic cooperation accord in 2013. In 2016, they inked a deal with India to develop a new transport corridor project stretching from the southern Iranian port of Chabahar into Afghanistan.

And yet, as I explained two years ago in Foreign Policy, none of this has stopped Tehran and the Taliban from having a long-standing relationship. When Mullah Mansour, the head of the Afghan Taliban, was killed in a drone strike in 2016 while driving in Pakistan, he was returning from a trip to Iran—where the Taliban opened an office in 2012.

Despite all their bloody differences, a common U.S. enemy is enough to bring the two sides together. Iran has long feared the United States will use Afghanistan as a staging ground for a strike on its nuclear facilities. The Trump administration’s hard line on Iran only deepens Tehran’s anxieties about the U.S. presence on its eastern flank.

Over the last decade, NATO forces have periodically intercepted Taliban-bound Iranian arms shipments. By 2015, according to Afghan and Western officials, Iran was increasing its supply of arms to the Taliban—while also starting to fund, recruit, and train their fighters.

Such allegations have intensified in recent months. Officials in western Afghanistan have claimed that Iran’s Revolutionary Guard has provided funding, shelter, money, and arms to Taliban fighters. The Taliban itself has acknowledged Iranian assistance. In July, a Taliban political advisor disclosed to the Times of London that in May, as Trump was preparing to pull out of the nuclear agreement, the Taliban reached a deal with Tehran to send fighters to Iranian military academies for six months of “advanced training.”