Let’s say Islamic State fighters attack an Israeli military patrol along the Syrian border. They try unsuccessfully to kidnap an Israeli soldier, and they kill four others. A Jordanian border post is hit, too, and the Islamic State proclaims it has control of Daraa province in southern Syria.

How do Israel and other key players respond? In a war game played here last week, they retaliated, but cautiously. The players representing Israel and Jordan wanted to avoid a pitched battle against the terrorists — they looked to the United States for leadership.

This simulation exercise was run by Israel’s Institute for National Security Studies (INSS) as part of its annual conference. The outcome illustrated the paradoxical reality of the conflict against the Islamic State: Israel and Jordan act with caution and restraint, hoping to avoid being drawn deeper into the chaotic Syrian war, even as the United States escalates its involvement.

“We all believe that keeping Israel out of the conflict is important,” said Brig. Gen. Assaf Orion, a retired officer who served as head of the Israel Defense Forces’ planning staff. He led the Israeli team in the simulation. In the war game, Israel retaliated for the killing of its soldiers but avoided major military operations.

Jordan, too, wanted to avoid escalation. The players representing Jordan didn’t want to send their own troops into Syria. They worried about refugees and terrorist sleeper cells inside Jordan. They hoped that the combined military power of Russia and the Syrian regime could suppress the conflict and evict the Islamic State from its foothold in southern Syria. They looked for U.S. leadership but weren’t sure it was dependable.

Which left the United States. Gen. John Allen, the retired Marine who until recently coordinated the U.S.-led coalition’s strategy against the Islamic State, played the American hand. The United States viewed Israeli and Jordanian security as a vital national interest, he said, and would send its warplanes to retaliate for any attacks on its allies. U.S. military involvement, in the simulation and in reality, is increasing — partly by default of others.

If you don’t like this simulated version of the war, you may like real life even less. There’s growing consensus that the Islamic State poses a severe threat to regional and even international order; one senior former Israeli official described the conflict with the caliphate as “World War III.” But most players still want to hold America’s coat while the United States does the bulk of the fighting.

A visit to Israeli military headquarters here confirmed that the war game was an accurate reflection of how Israeli military leaders see the conflict. Rather than attacking Islamic State forces along its northern and eastern borders, Israel pursues a policy of deterrence, containment and even quiet liaison, said a senior Israeli military official. He noted that if Israel wanted to mount an all-out ground attack on Islamic State forces in southern Syria and the Sinai Peninsula, it could wipe them out in three or four hours. “But what would happen the day after?” asked this Israeli military official. “Right now, we think it will be worse. So we try to deter them.”

The Israelis don’t want to disturb a hornet’s nest in taking on the Islamic State. Is a similarly measured option available to the United States? Most Israeli officials say no. They argue that the United States is a superpower, and that if it wants to maintain leadership in the region, it must lead the fight to roll back the Islamic State.

The theme of the INSS conference was that the rules of the game are changing in the Middle East. States are fragmenting; a self-proclaimed caliphate has taken deep roots in Syria and Iraq and now has a presence in many more countries around the world; a rising, still-revolutionary Iran is using proxy forces to destabilize nearly every Arab state; the old order embodied by the secular dynasties of the Mubaraks, Assads and Gadd afis is shattered.

Israelis disagree among themselves about nearly every political topic, but on the strategic picture, there is basic agreement: As the state system splinters in the Middle East, the instability in this region will be chronic, and it will persist for many years. Escaping this conflict will be impossible. So think carefully how you want to fight a war in what the senior Israeli military official called “the center of a centrifuge.”

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