Tension between Washington and Tehran has been a growing undercurrent of the war in Gaza, even as both countries tried to prevent it from sparking a direct confrontation during the first six months of fighting. Robin Wright, a joint fellow at USIP and the Wilson Center, explores the evolving flashpoints in the world’s most volatile region as well as the challenges for U.S. diplomacy, the new triggers for a wider regional conflagration and the historical backdrop.

Citizens walk near missile carriers and other weapons displayed during an event marking the 45th anniversary of Iran’s Islamic Revolution in Tehran, Iran, on Sunday, Feb. 11, 2024. (Arash Khamooshi/The New York Times)
Citizens walk near missile carriers and other weapons displayed during an event marking the 45th anniversary of Iran’s Islamic Revolution in Tehran, Iran, on Sunday, Feb. 11, 2024. (Arash Khamooshi/The New York Times)

What are the dangers to the U.S. of a wider war in the Middle East?

Tensions have sporadically escalated during the first six months of the Gaza war as the U.S. and Iran’s network of allies have increasingly been pitted against each other — in Gaza and beyond. The primary danger for the U.S. has been getting sucked into disparate roles — either as an ally or adversary, as an arms supplier or diplomatic broker— on other fronts. The Middle East has consumed top U.S. officials and diverted attention from China's ambitions in the Indo-Pacific and Russia’s invasion of Ukraine. A war that spawns greater instability in the Middle East could also impact the global economy. By April 7, the six-month mark of the Gaza war, the price of Brent crude oil — the benchmark — rose above $90 per barrel and could hit $100 per barrel by September, JPMorgan Chase predicted. The U.S. is active — and vulnerable — on multiple fronts.

Where is the U.S. deployed — and vulnerable?

The U.S. has more than 10,000 forces deployed across the Middle East — in Bahrain, Iraq, Israel, Jordan, Kuwait, Lebanon, Oman, Qatar, Saudi Arabia, northeastern Syria and the United Arab Emirates. After the Gaza war erupted, the U.S. also deployed two aircraft carrier groups in the Mediterranean and the Red Sea with more than 7,000 additional military personnel. They increased force protection, but they also became targets.

The most vulnerable are the 900 American forces deployed in northeast Syria and another 2,500 in Iraq. Both have been part of international coalitions to contain the remnants of ISIS, which still has active cells in both countries. U.S. forces were engaged in counterterrorism operations unrelated to Israel or Iran. Their small and scattered posts have nevertheless been hit dozens of times by Iranian-backed militias since the Gaza war erupted.

Another 350 Americans have been based at Tower 22, a Jordanian post on the border with Iraq and Syria to support Operation Inherent Resolve against ISIS. The U.S. also has hundreds of diplomats in the Middle East, although none in Iran — the nexus of threats against U.S. personnel, interests and allies.

What are the U.S. diplomatic options?

The U.S. has important leverage in the Middle East, although its influence has diminished amid the growing military and economic roles of Russia and China. It has faced a diplomatic balancing act. In April, President Biden threatened to shift U.S. policy on Israel if Prime Minister Benjamin Netanyahu did not do more to support a cease-fire that included the release of hostages by Hamas and more humanitarian aid to the Palestinians. In the same conversation, however, he vowed that Israel could count on American support for any threat from Iran. 

The U.S. has limited diplomatic options in dealing with the Islamic republic, with most of Iran’s allied militias already on the U.S. terrorism list. Washington has had no formal relations with Tehran since April 1980, after the then new revolutionary government refused to free dozens of American envoys seized in the U.S. Embassy takeover. It relies on messages relayed through Switzerland, which represents U.S. interests in Iran, or other allies. “We have the ability to send messages, very clear messages, to Iran both directly and indirectly, and we do so when it’s in our interest,” State Department spokesman Matthew Miller said on April 3.

But the political environment in Tehran has grown even more hostile to Washington since the election of President Ebrahim Raisi, in 2021, and a harder line parliament, in 2024. The U.S. had a short-lived direct channel to Tehran in 2013 during negotiations by the world’s six major powers to limit Iran’s nuclear program. Led by the U.S. in the final phase, the often-torturous talks produced a controversial deal with Iran in 2015. President Trump withdrew from it in 2018. Iranian envoys have since refused to talk directly to U.S. officials.

What are the U.S. diplomatic obstacles?

U.S. diplomacy in the Middle East was stuck on multiple fronts during the first six months of the Gaza war. The Hamas attack on Oct. 7, 2023 and the prolonged Israeli military response were unanticipated setbacks. Since 2020, the Trump and Biden administrations had concentrated on extending the Arab-Israeli peace process launched in the Abraham Accords. Both presidents personally tried to convince Saudi Arabia, the birthplace and guardian of Islam’s holy places, to recognize Israel as the most significant step to end a conflict that began in 1948. Of the 22 states in the Arab League, only six have formally recognized Israel. But the U.S. initiative froze in place as the Gaza war deepened.

Amid that impasse, Washington struggled to broker cease-fires and a post-war plan for Gaza. It helped orchestrate the first cease-fire, which lasted from Nov. 24 to 30, 2023. Hamas released 105 captives, including some foreign workers, and Israel freed 240 Palestinian prisoners. For months, senior U.S. officials then held several rounds of talks with Egyptian, Qatari and Israeli officials on a second cease-fire to last six weeks. It was unlikely, however, to end the Gaza war, which both Israel and Hamas defined as an existential conflict — or a fight to the finish of the other. Washington faced similar obstacles in navigating terms to end thousands of cross-border attacks between Israel and Hezbollah. The region became a diplomatic quagmire.

What have been the triggers for a wider war?

During the first six months of war, hostilities between Israel and Hamas spilled onto other fronts in the Middle East. Militias aligned with Iran escalated attacks on Israel as well as U.S. forces deployed in the Middle East and international shipping in the Red Sea. They vowed to continue their campaigns until the Gaza war ended. The triggers played out in disparate arenas.

In January 2024, a drone strike killed three American forces and injured 40 others deployed at Tower 22 in Jordan. The Pentagon implicated Kataib Hezbollah, an Iranian-backed group that operates in both Iraq and Syria. “We know that Iran is behind it,” Deputy Pentagon Press Secretary Sabrina Singh told reporters. “Iran continues to arm and equip these groups to launch these attacks, and we will certainly hold them responsible.” The attack was the first time that Jordan, a close U.S. ally, was drawn into the standoff between Washington and Tehran.

The U.S. hit back on February 2 with a blitz of airstrikes — 125 precision munitions fired on 85 targets at seven facilities spread across Syria and Iraq. Each site was used by Iran's Revolutionary Guards “and affiliated militias” to attack U.S. forces, Defense Secretary Lloyd Austin said in a statement. The counterstrikes were just “the beginning of our response. There will be more steps,” National Security Advisor Jake Sullivan told ABC News. “Some of those steps will be seen, some may not be seen. But there will be more action taken to respond to the tragic death of the three brave U.S. service members.”

Tensions escalated further in April, when Israel launched an unprecedented attack on an Iranian diplomatic facility in Damascus. The airstrike, by two U.S.-made F-35s, killed three generals in the Revolutionary Guards and other officers in a building abutting the Iranian embassy in Syria. It was leveled. The attack reportedly coincided with a meeting between the Revolutionary Guards and a Palestinian militia to discuss the war in Gaza. Among the dead was General Mohammad Reza Zahedi, the Revolutionary Guard coordinator of Iran’s covert operations in Syria and Lebanon.

All U.S. forces were put on high alert after the Israeli attack. “We have made clear directly to the Iranian Government that it should not use this incident as a pretext to attack American troops or American facilities in the region,” Miller, the State Department spokesman, said on April 8. “And we will continue to make clear to them that they should not take any escalatory actions.” 

Who is now making threats of a wider war?

The dangers of a wider war were reflected in the increasingly inflammatory language as the Gaza war hit the six-month mark. Iran vowed revenge for the Israeli attack on its generals in Syria. “The time, type, plan of the operation will be decided by us, in a way that makes Israel regret what it did,” General Mohammad Bagheri, a Revolutionary Guard commander on Iran’s Joint Chiefs of Staff, said at the April 6 memorial for the slain Iranian officers. “This will definitely be done.” A second general issued a broader warning that no Israeli embassies were safe anymore.

In Lebanon, Hezbollah leader Hassan Nasrallah said that his forces had not yet used it major weapons in their attacks on northern Israel. The militia is estimated to have more than 150,000 rockets and missiles. “The Resistance in Lebanon doesn’t fear war. We are fully ready to engage in a war that the enemy will regret,” he said in a televised speech on April 5 to mark the annual Quds Day. The event was created by Iran after the 1979 revolution to support Palestinians and oppose the Israeli occupation. “The enemy knows well what a war with Lebanon means, if they want war then hello and welcome!” Nasrallah boasted.

Israel issued its own warnings. General Herzi Halevi, chief of the Israel Defense Forces, vowed that his military knew how to deal with Iran “offensively and defensively. We prepared for this. We have good defense systems. We know how to act powerfully against Iran in places near and far," he said on the six-month anniversary of the Gaza war.

Naftali Bennet, the former Israeli prime minister, said Israel needed to be more persistent in directly targeting Iranian assets. “Iran is an octopus of terror,” he told CNN on April 7. “Its head is in Tehran and then it sends its tentacles all around Israel and the Middle East.” Tehran “loves to use other people’s lives” to promote its agenda. Its allies “have been pounding Israel using their arms while their head was sort of immune,” Bennet said. “So the age of immunity for Iran’s head is over.”

What is the historic backdrop of tensions?

Iran and Israel have engaged in an increasingly deadly shadow war since 1982, when Israel invaded Lebanon to force the Palestine Liberation Organization away from the southern border. The biggest unintended consequence of the conflict was the emergence of Hezbollah among Shiites, who dominated southern Lebanon and became enraged by Israel’s occupation. Iran tapped into Shiite fury to foster, train, and arm the embryo of Hezbollah.

As it grew, the Lebanese militia repeatedly targeted Israeli troops during their 18-year occupation of the south. The U.S. was sucked into their war. In 1983, the first generation of Hezbollah operatives bombed U.S. peacekeepers in Beirut, killing 241 marines and naval personnel. It was the largest loss of U.S. military life in a single incident since Iwo Jima in World War II. For Israel, Hezbollah evolved into a far greater threat than the PLO had ever been. And Lebanon became the frontline for Iran’s effort to eliminate Israel and elevate its own influence across the Middle East.

In 1985, Yitzak Rabin, then the Israeli defense minister, reflected, “Among the many surprises, and most of them not for the good, that came out of the war in Lebanon, the most dangerous is that the war let the Shiites out of the bottle. No one predicted it; I couldn’t find it in any intelligence report.” He warned that if Israel’s war in Lebanon had resulted in the PLO being replaced by Shiite extremism, “we have done the worst [thing] in our struggle against terrorism.” Lebanon’s Shiites “have the potential for a kind of terrorism that we have not yet experienced.”

What was the tipping point?

The rise of Hezbollah transformed the Middle East. Israel had fought four wars between 1948 and 1973 — all against the armies of states. Between 1982 and 2000, Hezbollah was the first non-state actor to engage in a war that forced a unilateral military withdrawal. In 2000, Israel opted to end what had become known as its Vietnam. “This 18-year tragedy is over,” Prime Minister Ehud Barak said at the time. Then Foreign Minister David Levy declared that the withdrawal meant that Israel was “regaining control of the initiative.”

Yet Hezbollah was not disarmed. Hostilities across the border continued. Israel fought a second war in Lebanon in 2006 after a Hezbollah incursion across the border captured Israeli soldiers. That war lasted 34-days — Israel’s longest war until 2024. It, too, ended with an Israeli withdrawal from southern Lebanon and without enduring terms to stabilize the border.

Hezbollah was the first strategic success for Iran’s revolutionary regime. It marked the beginning of a trend that spread across the Middle East. Militias in Iraq, Yemen, the Palestinian territories and Syria now share the long-term goal of defeating Israel and forcing U.S. troops out of the Middle East.

Where do things stand in 2024?

Between 1982 and 2024, Iran built the most powerful and well-armed alliance in the Middle East — with branches from the Mediterranean across the Red Sea to the shores of the Persian Gulf — dubbed the Axis of Resistance. It also developed an independent arms industry. By 2024, the largest share of the world’s drones in use were manufactured in Iran, the Global Terrorism Trends and Analysis Center reported. Iran’s nuclear advances also narrowed the time required to produce a bomb.

Over the decades, U.S. and Israeli counterstrikes on Iranian allies in Lebanon, Syria, Iraq and Yemen have had impact. Some militia arms were destroyed. Military infrastructure was disabled. Smuggling routes were hit. Leaders and fighters were killed. In January 2020, a U.S. airstrike assassinated General Qassem Soleimani, commander of the Quds Force and the mastermind of Iran’s covert activities across the Middle East, and the leader of Kataib Hezbollah in Iraq.

Yet attacks by the Axis of Resistance did not stop, even as Tehran demonstrated what the Iranian media called “strategic patience” in not directly taking on the U.S. with its own assets. During the first six months of the Gaza war, Iran’s allies all escalated their separate campaigns, claiming sympathy with Hamas. By April 2024, Iran and its disparate allies were linked to the deaths, directly or indirectly, of thousands of Americans and Israelis in suicide bombings and hostage-takings as well as rocket, drone and missile attacks over four decades. And there was no end in sight.

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