A SHOW OF FORCE

The Taliban finally conceded Sept. 10 that "renegade" troops acting without orders did kill the diplomats and a journalist when they captured the northern city of Mazar-i-Sharif on Aug. 8. According to the sole survivor, the Iranians were lined up and shot in the basement of Iran's consulate. Then came reports, from Amnesty International and diplomats, that at least 4,000 Hazara civilians, including children, were butchered as the Sunni Taliban secured Mazar. The Hazara are Shi'a and look to Iran for spiritual guidance. Crowds in Tehran called for revenge.

But even while building up forces on the border, Iran has stressed a desire to defuse tensions without recourse to war. Many officials are wary of a protracted fight in a country that has been a graveyard for foreign invaders. Tehran's restraint was evident on Sept. 21, when President Mohammad Khatami said to the U.N. General Assembly: "There is no military solution" for the Afghan crisis. Iran's deputy foreign minister, attending a Sept. 21 meeting at the U.N. between Russia, the United States and Afghanistan's six neighbors, also said: "We have made finding a diplomatic solution our priority."

The group of eight called on the Taliban to agree to an international investigation into the reported mass killings and to open talks with its rivals about sharing power. The Taliban were not represented at the meeting since the international community does not recognize the militia as the legal government. But Mawlawi Abdurrahman Hotak, the Taliban deputy minister of information, later ruled out negotiations with the two remaining opposition groups since the Taliban control about 90% of the country. Meanwhile, rocket attacks on Kabul killed at least 76 people and wounded more than 230 on Sept. 20 and 21. The strikes were the deadliest in two years. The Taliban and local residents have blamed the forces of opposition leader Ahmadshah Massoud, who is supported by Iran and whose troops are poised just north of Kabul.

The Taliban may not be willing to negotiate with its rivals now. But before Iran sends its troops back to barracks, the militia may have to make more concessions than it has so far. Last week in a "gesture of goodwill" the Taliban released five truck drivers from among some 40 Iranian prisoners held in the southern city of Kandahar. Several said they had been tortured. However, Iran's key demands - an apology and the extradition of the diplomats' murderers - have been ignored.

Iran not only holds the Taliban responsible for the deaths, it also blames the militia's sponsor, Pakistan. Islamabad has backed the Taliban since the movement's inception in 1994 and diplomatic sources believe that its Inter-Services Intelligence Directorate was privy to planning for the latest Taliban campaign to conquer the north. The offensive began as Islamabad was ostensibly trying to involve Tehran in a joint peace initiative.

Pakistani Foreign Minister Sartaj Aziz hurried to Tehran Sept. 17 on a damage-control mission. His Iranian counterpart, Kamal Kharazi, was blunt, telling Aziz that "the prevention of further escalation requires political resolve and practical steps by the Pakistani government." Translation: Rein in the Taliban. Trouble is Pakistan may be unable to do so - even if the intelligence agency and the military agree a new policy is needed to avoid war and Pakistan's growing diplomatic isolation. With victory apparently in reach, the Taliban are now less likely than ever to moderate their behavior. "We cannot control them," a Pakistani official conceded to Asiaweek.

With U.N. special envoy Lakhdar Brahimi due to return to the region in early October, international diplomacy may yet forestall war. But should that fail, Tehran has various military options. It has the capability to mount a full-scale invasion aimed at seizing Kabul. It is very unlikely to do so. "Holding open lines of supply against stiff guerrilla resistance and then trying to establish a regime in Kabul would be a total nightmare," says one military observer. "And they know it." A more prudent option might be a drive into western Afghanistan that would take the Persian-speaking city of Herat and a border buffer zone, while also cutting off the Taliban's northern forces from Kabul and the south. Herat has been chafing under hardline Taliban rule; its residents would probably welcome the Iranians as liberators.

If Tehran wants to avoid committing ground forces, it could simply launch punitive air strikes against the only remaining strategic targets left in Afghanistan - several Taliban-held airbases. While satisfying the domestic appetite for revenge, the strikes would not alter the balance of forces in Afghanistan or help Iran-backed Massoud. A minimum response might be to recruit and train guerrilla fighters from the 1.4 million Afghan refugee community in Iran and send them back across the border. But that would take time. "It's not going to satisfy those who want revenge now and it won't be much help to Massoud," says a military analyst.

Iranian leaders may finally feel compelled to act. "They can't just walk away from this now," says a Western military official in Islamabad. "They have to do something." And with nearly 250,000 troops to supply on the border, they may have to do something soon.