Iran has achieved four of the five basic goals. It has created secure frontiers and is in control of the population inside the country. The greatest threat against Iran is the one it has faced since Alexander the Great — that posed by major powers outside the region. Historically, before deep-water navigation, Iran was the direct path to India for any Western power. In modern times, the Zagros remain the eastern anchor of Turkish power. Northern Iran blocks Russian expansion. And, of course, Iranian oil reserves make Iran attractive to contemporary great powers.

There are two traditional paths into Iran. The northeastern region is vulnerable to Central Asian powers while the western approach is the most-often used (or attempted). A direct assault through the Zagros Mountains is not feasible, as Saddam Hussein discovered in 1980. However, manipulating the ethnic groups inside Iran is possible. The British, for example, based in Iraq, were able to manipulate internal political divisions in Iran, as did the Soviets, to the point that Iran virtually lost its national sovereignty during World War II.

The greatest threat to Iran in recent centuries has been a foreign power dominating Iraq — Ottoman or British — and extending its power eastward not through main force but through subversion and political manipulation. The view of the contemporary Iranian government toward the United States is that, during the 1950s, it assumed Britain’s role of using its position in Iraq to manipulate Iranian politics and elevate the shah to power.

The 1980-1988 war between Iran and Iraq was a terrific collision of two states, causing several million casualties on both sides. It also demonstrated two realities. The first is that a determined, well-funded, no-holds-barred assault from Mesopotamia against the Zagros Mountains will fail (albeit at an atrocious cost to the defender). The second is that, in the nation-state era, with fixed borders and standing armies, the logistical challenges posed by the Zagros make a major attack from Iran into Iraq equally impossible. There is a stalemate on that front. Nevertheless, from the Iranian point of view, the primary danger of Iraq is not direct attack but subversion. It is not only Iraq that worries them. Historically, Iranians also have been concerned about Russian manipulation and manipulation by the British and Russians through Afghanistan.

The Current Situation

For the Iranians, the current situation has posed a dangerous scenario similar to what they faced from the British early in the 20th century. The United States has occupied, or at least placed substantial forces, to the east and the west of Iran, in Afghanistan and Iraq. Iran is not concerned about these troops invading Iran. That is not a military possibility. Iran’s concern is that the United States will use these positions as platforms to foment ethnic dissent in Iran.

Indeed, the United States has tried to do this in several regions. In the southeast, in Balochistan, the Americans have supported separatist movements. It has also done this among the Arabs of Khuzestan, at the northern end of the Persian Gulf. And it has tried to manipulate the Kurds in northwestern Iran. (There is some evidence to suggest that the United States has used Azerbaijan as a launchpad to foment dissent among the Iranian Azeris in the northwestern part of the country.)

The Iranian counter to all this has several dimensions:

1. Maintain an extremely powerful and repressive security capability to counter these moves. In particular, focus on deflecting any intrusions in the Khuzestan region, which is not only the most physically vulnerable part of Iran but also where much of Iran’s oil reserves are located. This explains clashes such as the seizure of British sailors and constant reports of U.S. special operations teams in the region.

2. Manipulate ethnic and religious tensions in Iraq and Afghanistan to undermine the American positions there and divert American attention to defensive rather than offensive goals.

3. Maintain a military force capable of protecting the surrounding mountains so that major American forces cannot penetrate.

4. Move to create a nuclear force, very publicly, in order to deter attack in the long run and to give Iran a bargaining chip for negotiations in the short term.

The heart of Iranian strategy is as it has always been, to use the mountains as a fortress. So long as it is anchored in those mountains, it cannot be invaded. Alexander succeeded and the Ottomans had limited success (little more than breaching the Zagros), but even the Romans and British did not go so far as to try to use main force in the region. Invading and occupying Iran is not an option.