NEW YORK — There’s a lot to be optimistic about today. In almost every part of the world, economies are growing and war, poverty and disease are receding. But then there is the Middle East.

Syria remains a collapsed country; more than 5 million of its people have already fled. Yemen is now the site of the world’s worst famine, and the war there seems unlikely to end anytime soon. Iraq, barely recovered from its own civil war and battle with the Islamic State, estimates it needs around $100 billion for reconstruction — money it does not have. And the danger of greater conflict in the region seems ever-present. We are now seeing fighting between Turkey and American proxies, and fire exchanged between Israel and Syria. Recently, U.S. airstrikes killed perhaps dozens of Russian mercenaries in Syria, a worrisome escalation for the former Cold War adversaries.

In dealing with the volatile situation, the Trump administration seems largely disengaged. Its strategy, if it can be called that, has been to double down on its anti-Iranian stance — subcontracting foreign policy to Israel and Saudi Arabia. But recent events make plain it’s not working.

In the latest issue of Foreign Affairs, the scholar Vali Nasr urges a fundamental rethinking of Washington’s Iran policy. The administration is acting on the assumption that instability in the Middle East is the result of a rising Iran that seeks to spread its ideology. Iran is often described in the corridors of Washington as “more interested in being a cause than a country.”

Nasr points out that this premise is wrong. Today’s instability in the Middle East did not originate with Tehran’s ambitions. It was the result of the 2003 American invasion of Iraq, which overturned the balance of power between Arab states and Iran by dislodging Saddam Hussein and allowing chaos to spread. Iran pursued its national interests intensely, seeking influence in its neighborhood. It did not try to spread Islamic fundamentalism; in fact, it has been at the forefront of the fight against Sunni terrorist groups like the Islamic State.

Iran’s strategy has been remarkably successful because it ventures into places where it has strong local allies (Iraq, Syria, Yemen), is willing to put in troops and militias, and plays a long game. Its adversaries, by and large, do not have these advantages. The United States and Israel — outsiders in the Arab world — mostly fight from the skies. But air dominance has its limitations in terms of shaping political realities on the ground. It’s highly significant, Nasr explained to me, that Syria (backed by Iran and Russia) was able to down an Israeli fighter jet. “It’s the first time in 30 years that an Israeli military strike has been met with a response. It underscores how difficult it will be to dislodge Iran and Russia from Syria.”

Meanwhile, Turkey has been taking increasingly bold actions in northern Syria against American-backed Kurdish forces. This raises the possibility that, at some point, Turkey and the United States — two NATO allies — might find themselves firing on each other.

Where are the Arab countries in this geopolitical game? “The most striking reality about the power struggle in the Middle East these days,” Nasr told me, “is the absence of the Arabs. Look at the recent fighting. It is all non-Arab powers — Iranians, Turks, Russians, Israelis and Americans — engaged in combat operations to determine who will shape the Arab world.”

At this point, far from being a revolutionary power, Iran is trying to ratify the status quo, largely because it has won. Its presence in Iraq and Syria is now entrenched. Its ally Bashar Assad has survived and is consolidating power over a rump Syria. Saudi Arabia’s efforts to fight Iranian influence in Yemen, Lebanon and Qatar have so far failed. Qatar is now closer to Iran and Turkey, and the rifts within the Arab world continue to deepen.

For its part, Russia — having aligned itself with Iran while still maintaining close ties with Israel — has emerged as the kind of outside balancer that America once was. “Russia … has become the only power broker in the Middle East that everyone talks to,” writes Nasr in Foreign Affairs. This is not because Russia is powerful, but because it has been shrewd.

Since 1973, when Henry Kissinger essentially expelled the Russians from the Middle East, the United States has been the preeminent outside power. It is losing that role through a combination of weariness, disengagement and a stubborn refusal to accept the realities on the ground. A different American approach — engaging with Iran and working with Turkey and Russia — might return it to its unique place in the region and help create a more stable balance of power in what remains the world’s most volatile hot spot.

Fareed Zakaria is a columnist with The Washington Post. His email address is: comments@fareedzakaria.com.

Fareed Zakaria