The Middle East is in a new era, very different from the politics and strategic situation we have been used to for so long. For 55 years the region has lived under Arab nationalist dominance. Every Arab regime, except perhaps Sudan, is Arab nationalist, governed by that basic system and world view. Of course, these regimes have governed badly, not keeping pledges to unite the Arab world, minimize Western influence, destroy Israel or bring rapid social and economic progress. Still, they know how to stay in power. Remember that the last real regime change from within an Arab state happened 37 years ago, when Hafez Assad seized power in Syria. Since then, surprisingly little has changed in Arab ideology, political structure, economic organization or society. It has also been 28 years since Iran's Islamist revolution took power in 1979. Since then - though not solely because of that event - Islamism has been on the upsurge. Certainly, it also suffered setbacks and almost three decades later was unable to seize power anywhere, at least until Hamas's recent triumph in Gaza. WHAT HAS happened now, however, is that radical Islamism has reached a critical mass. It poses serious challenges to Arab nationalism as the leading opposition in every Arabic-speaking country. Islamism plays a key role in governing Iraq; Hamas defeated Fatah on the Palestinian front; and Hizbullah is close to gaining at least equal power in Lebanon. For years, probably decades, to come, the Middle East will be shaken by a titanic battle for control between Arab nationalism and Islamism. This struggle, and certainly not the Arab-Israel conflict, is the central theme and underlying factor in every regional issue. This is so for several reasons. One is that the Islamist cause is now promoted by an alliance including two regimes, Iran and Syria, as well as Hamas and Hizbullah, which both rule territory. Syria's government, technically "secular" and ruled by an Alawite minority, behaves like an Islamist one, especially in its foreign policy, so as to keep loyal its Sunni Muslim majority. It is folly to think that this HISH alliance (Hamas-Iran-Syria-Hizbullah) can be split. After all, the parties have common aims and ideologies, their cooperation is so mutually beneficial - and, last but not least, they think they are winning. Historically, there were two barriers to Iran's trying to become the Middle East's leading power: the Persian-Arab and Shi'ite-Sunni divides. How could Persian, Shi'ite Iran appeal to Arabs who mostly were Sunni? The HISH alliance solves that problem. Three of the four members are Arab, and Hamas is Sunni, as is the majority of Syrians. If one adds Iraq's Sunni Arab insurgency, that breakthrough becomes even clearer. Nor does this exhaust the Islamist forces working today to seize state power throughout the region. Al-Qaida is a factor, mostly in Iraq - where it cooperates closely with Syria - and Saudi Arabia. Al-Qaida is far more a threat in terms of terrorism, however, than in a strategic sense. Since it has only one tactic, flexibility, in comparison to other Islamists, al-Qaida is unlikely to take over any countries. A third Islamist set of groups are Muslim Brotherhood movements. While Hamas arises from the Palestinian Muslim Brotherhood, its Egyptian, Jordanian and Syrian counterparts do not particularly like Iran or Shi'ites. Still, they are also trying to transform Arab nationalist states into Islamist states. Even if they use elections in pursuing this objective, the goal remains the same. TO UNDERSTAND the region today, all its issues have to be seen in the context of this nationalist-Islamist battle. If Iran gets nuclear weapons it will greatly increase the power of HISH, the Arab regimes' readiness to appease it, and the recruitment for Islamists of all types throughout the area. In Lebanon, Hizbullah, backed by Iran and Syria, seeks to control the government, or at least have veto power over its policies. In Iraq, Syrian-backed Sunni insurgents fight Shi'ites, among whom Iran has considerable influence. HISH hedges its bets, but on both sides tries to turn Iraq into a client state. Among Palestinians, Hamas seeks full power by ensuring that war with Israel continues, and by driving Fatah out of the West Bank. On the other side, in theory, are all the Arab regimes, except Syria, plus Israel. In practice, though, these forces are far from united. Arab governments will try to cut their own deals or pursue their own interests. They may be privately happy if Israel defeats Hamas or Hizbullah, but they will scarcely provide any help, or make peace. A good example here is Saudi Arabia. The Saudis fight Iran, but do so by giving money and recruits to the Iraqi insurgency - or by their ill-fated attempt to buy off Hamas by brokering a deal between it and Fatah. Neither of these tactics has been very helpful. And the incompetence, corruption and dictatorial nature of the Arab regimes - plus their Islamist-style extremist propaganda - all help foster more opposition. Still, this does not at all mean the Islamists will win. No one should underestimate the Arab nationalist regimes, and there are huge problems with the Islamists' strategy. What is vital, however, is to understand that past realities are now outmoded; and myths that are all too often dominant in media and academia are even more misleading. The writer is director of the Global Research in International Affairs Center and editor of Middle East Review of International Affairs.