President Bush has issued a stern warning to Iran not to try to undermine the interim government in Afghanistan by sending arms to local warlords or harboring al-Qaida fighters. But Iran says the accusations are unfounded and cites its own contribution to the defeat of the Taleban.

U.S. special forces say they have seen Iranians bribing and threatening tribal leaders across the border in Afghanistan and supplying them with arms as well. They also say Iran is giving refuge to fleeing al-Qaida fighters. In response, President Bush told Iran to stop these activities or face the consequences, which he said would be diplomatic, initially.

Nothing new about this, says Anwar Ahady, professor of political science at Providence College. Foreign powers have been interfering in Afghanistan for their own ends for years. Iran is only the latest example.

But it should be stopped, says Professor Ahady, along with similar efforts by the other neighboring countries. "It would really be detrimental to political stability in Afghanistan if Iran were to cultivate relations with warlords, with governors or with political groups and not to have state-to-state relations with Afghanistan," says Professor Ahady. "I can understand the concern on the part of the other actors, including the international community and the United States."

Iran has strong ties to western Afghanistan, which are not easily broken, says Larry Goodson, professor of international studies at Bentley College and author of "Afghanistan's Endless War." Herat, the region's principal city, has a Persian as well as an Afghan character, and its people share a common culture with Iran.

In a celebrated episode, province commander Ismail Khan escaped from a Taleban prison and fled to safety in Iran. In return, he called Iran the ideal Islamic country.

Professor Goodson says Mr. Khan is a good leader who runs Herat with a firm, but benevolent hand, an enlightened warlord who sets an example for the others. He was disappointed with what he received at the Bonn meeting, only one ministry in the interim government for the five provinces under his control.

"Quite naturally, he said, OK, forget about Kabul. I am going to concentrate on shoring up my base here in Herat and in the surrounding provinces," says Professor Goodson. "If I am not going to get it from the government in Kabul, then I am going to look elsewhere." And where is elsewhere? Well, it is Iran."

That, of course, is fine with Iran, says Professor Goodson. A loyal ally makes it easier to infiltrate western Afghanistan. "It's really for Iran the most important place in Afghanistan, and Iran has moved, just as all of the regional powers have moved, into the continuing vacuum that exists in Afghanistan," he says. "We are unwilling to step in ourselves and prevent the vacuum from existing."

Simply complaining about Iranian or any other interference will not work, says Professor Goodson. A sizable U.S. or international force is needed to keep warlords and their outside supporters in line. Money will not convince them. They have others sources, like drug trafficking.

The way to bring unity to Afghanistan, says Professor Goodson, is to embark on a robust reconstruction, starting with the nation's ruined roads. "If we attacked the rebuilding of the roads with the same ferocity that we attacked the Taleban front lines when we bombed them, if we really came in with the army corps of engineers, doing what we had to do to certain warlords who wanted to delay that process or snipe at the engineers, imagine how that would look to the rest of the world and imagine what that would do for the Afghan people," says Professor Goodson.

It is an old saying, says Mr. Goodson, that if you give the Afghans roads, everything else will follow.