Iran is emerging as a key player in discussions on a post-Taliban Afghanistan. Over the past week, four high-level European diplomats have traveled to Tehran seeking Iranian support for a plan that would establish an interim Afghan government with the backing of the United Nations.

Iranian officials have expressed interest in cooperating with the Western-led anti-terrorism coalition, but they caution that they have only limited ability to influence developments in Afghanistan. At the same time, Iranian officials suggest that the anti-terrorism coalition should develop incentives for Iran and other states with interests in Afghanistan.

France's special envoy Pierre Lafrance, Italy's Foreign Minister Renato Ruggiero, UK Advisor on Afghanistan Robert Cooper, and German Foreign Minister Joschka Fischer have all walked through the towering blue and white arched entrance of Tehran's Foreign Ministry building in downtown Tehran with essentially the same message: "Please use your influence with the Northern Alliance to prevent them from taking over the country before the interim government is formed."

Iran has supplied the Northern Alliance, a collection of mainly Tajik and Uzbek anti-Taliban militias, with arms and intelligence. Iranian intelligence officers regularly meet with Northern Alliance commanders. Diplomats in Tehran say that information gleaned from those meetings is regularly relayed to India and Russia, which also support the Northern Alliance.

Iran, a majority Shi'a Muslim country, has opposed the Sunni extremist Taliban since the movement's takeover of Afghanistan in 1996. Publicly, Iran says the Taliban's extremist version of Islam gives the faith a bad name. Privately, Iranian officials worry about the Taliban's anti-Shi'a views, and the presence of a hostile regime backed by two regional powers – Pakistan and Saudi Arabia – on Iran's border.

Sharing a 600-mile frontier with Afghanistan, Iran hosts about 2 million Afghan refugees, who have fled that country since 1979, when the decade-long Soviet occupation began. Iran and Afghanistan nearly came to blows after Taliban forces killed 11 Iranian diplomats in Mazar-i-Sharif in 1998, during an offensive against the Northern Alliance.

Leaders of the anti-terrorism coalition are encouraging the development of a multi-ethnic Afghan political coalition, under the auspices of former King Mohammed Zahir Shah, to govern Afghanistan. Long-standing mistrust and hostility among the country's main ethnic groups – Pashtuns, Hazaras, Tajiks and Uzbeks – complicate the effort. Ethnic rivalries have been exacerbated by the nearly 13 years of civil war that followed the Soviet withdrawal in 1989.

The Northern Alliance has agreed to participate in the Zahir Shah initiative on the condition that is representatives hold up to half the 120 seats in a Supreme Council for the Unity of Afghanistan. But some observers express concern that the Northern Alliance's support for the Zahir Shah process is tenuous.

Washington and its Western allies see the Zahir Shah initiative as the best hope for a stable, peaceful post-Taliban transition. Many Western officials worry that a sudden Northern Alliance offensive that resulted in the fall of Kabul or in revenge massacres of Pashtuns could endanger the Zahir Shah initiative.

Thus, the question of Iran's influence on the Northern Alliance continually comes up in Tehran's discussions with Western and UN officials. "If Iran could rein in the Northern Alliance, we would be deeply grateful. It would make life much easier for us," said one Western diplomat.

An Iranian official, speaking on condition of anonymity, indicated that Tehran has the ability to exert pressure on the Northern Alliance, but he offered no guarantee that the anti-Taliban forces would listen.

"We are not without influence," the official said. But "their children have died at the hands of the Taliban. They have seen their country destroyed by these people. I'm not sure we could stop them from taking revenge even if we tried, but we could show them that it would be in their best interest to not do so."

It is unlikely that the Northern Alliance could rebuff Iran, India and Russia if the three states pressured the anti-Taliban forces to accept the UN-backed peace plan. However, the question is: What would Tehran, Moscow and New Delhi receive in return for using their influence?

"Aha, that is the right question," the Iranian official said.

Any meaningful incentives for Iranian cooperation would have to come from the United States since the European Union, which already has strong commercial ties with Iran, would have fewer carrots to offer. Possible carrots include a lifting of US sanctions on Iran, the withdrawal of US opposition to Caspian Sea pipelines traversing Iran and an end to US attempts to isolate Iran internationally.

Iran would also like to see a greater level of internationalization in the anti-terrorism effort. Iran is wary about overt American influence on the Zahir Shah initiative, and has repeatedly demanded a UN-backed solution.

"Afghanistan needs unity," the Iranian official continued, "but it should be a unity based on the wishes of the Afghan people, not on the hand-picked favorites of Western powers or Pakistan."

"We would be uncomfortable if we saw the UN being used as a tool for US policy," the Iranian official said. "If it is truly a UN operation, we would feel better."

The White House and the State Department have expressed interest in a gradual rapprochement with Iran, but the US Congress has yet to demonstrate a willingness to expend political capital on the Iran issue. Unless the recent European diplomatic visitors to Iran carried positive messages from the United States, Iran will likely retain a stance of benign neutrality on the issue of reining in the Northern Alliance.