The conflict between Arabs and Jews over the land between the Jordan Valley and the Mediterranean Sea - centered around the y city of Jerusalem, which is now the capital of the State of ael - has lasted for more than a hundred years. But now the conflict is changing - and not for the better.

It began under the rule of the Ottoman sultans and continued after World War I, when a League of Nations mandate offered a thin disguise for what was in fact colonial rule by the two European victors, Great Britain and France. Then came World War II, ending in the fall of the Nazi regime in Germany. In 1947, a two-thirds majority in the newly created United Nations agreed to a partition plan for the mandate territory of Palestine; and in 1948, with the expiration of the mandate, the State of Israel was founded.

That led to the first Middle East war between Israel and its Arab neighbors, who were defeated within a year, resulting in a mass displacement of many Arabs from the contested land (an event known as the Nakba, meaning "catastrophe"). But more wars would follow over the coming decades, resulting in more displacements and expulsions.

Throughout this century-long struggle, the wider world has undergone vast and profound geopolitical changes, from the fall of the old colonial empires to the two world wars and the long Cold War. Yet the Israel-Palestinian conflict has remained predominantly a regional affair, or even merely a local one between two small populations. Unlike the crisis in Sarajevo in the summer of 1914, this conflict has never sparked a global conflagration or a clash of great powers, culminating in a world war. But now that geopolitical reality, too, may be giving way before our very eyes.

It has been almost year since Hamas attacked Israel's border area with Gaza, massacring civilians and taking hundreds of hostages - including young and old, women and children. The resulting war in Gaza has taken a horrifying toll on Palestinian civilians, among whom Hamas militants hide and stash weapons caches. But from the very start, this war has been more than just another bloody chapter in the century-old Jewish-Palestinian conflict over the same land. The undeniable broader context is the struggle for regional hegemony between Iran and its "Axis of Resistance" and those who oppose it.

Ever since Iran launched an unprecedented missile attack against Israel from its own territory on April 13, the two have been in an undeclared state of war, and not over any piece of land. This conflict has a much larger dimension, because as long as Israel - one of the strongest military powers in the Middle East - exists, Iran cannot achieve its goal of regional hegemony. For Iran, then, Israel is primarily a means to that end. The Jewish state provides it with a crucial advantage over its main Arab rival, Saudi Arabia, by furnishing a raison d'être for Hamas, Hezbollah, and other participants in the Axis of Resistance.

Iran's advanced nuclear program is another means to the same end. A nuclear-armed Iran would shift the balance of power in the Middle East, and probably globally, too.

Now that the specter of a large regional war in the Middle East has been summoned, it is unlikely that anyone will be able to restrain it. Iran and its proxies have vowed revenge for Israel's recent assassinations of senior Hamas and Hezbollah officials in Tehran and Beirut, respectively. In a dramatically changing, increasingly unstable world, the century-old Middle East conflict has become something new. All the great powers are already involved - since Iran is a close partner to Russia and China - and the region's status as a major energy exporter means that any further escalation will bring severe global economic disruptions.

As in the 1970s, the Middle East has the potential to trigger a global economic crisis. This time, however, no viable solutions are in sight. All the parties involved are stubbornly convinced of their own chances, and neither the Palestinians nor the Israelis will ever simply give up.

By risking a wider war with Israel and the United States in its pursuit of regional hegemony and nuclear weapons, the Iranian regime could well bring about its own end. But in the meantime, Israel will continue to isolate itself internationally by pressing its brutal military campaign in Gaza. Both sides have renounced reason, and that should concern us all.

From Project Syndicate