Saudi warplanes targeted Iranian-backed militants in Yemen this week as part of an effort to check Tehran’s influence in the region. (Nabeel Quaiti/Reuters)

Yochi Dreazen is managing editor for news at Foreign Policy.

Saudi Arabia has sent its warplanes roaring into Yemen to hammer an Iranian-backed Shiite militia. In Iraq, forces armed and trained by Iran have been battling a Sunni militia that received fighters and money from Saudi Arabia. And thousands of miles away, the Obama administration is grappling with a new crisis: The Middle East’s longest-running cold war may be about to turn hot.

Saudi Arabia and Iran, the Islamic world’s leading Sunni power and its leading Shiite one, have spent decades quietly funneling weapons and money to allied forces throughout the region in an attempt to build up their own influence at each other’s expense. They have jousted in the shadows, allowing proxies to do the fighting and dying. But Riyadh’s push into Yemen exposes that conflict to the entire world — and could lead to open combat between the two nations.

Saudi Arabia was Yemeni President Abed Rabbo Mansour Hadi’s patron, and his ouster by Houthi rebels set in motion events that now have Saudi forces directly battling Iranian-backed ones. Reports from the region suggest that Saudi planes are going out of their way to hit known Iranian targets inside Yemen, including ports that Iran is believed to be using to store and ship weapons. Those strikes could easily result in Iranian fatalities at Saudi hands.

Iranian and Saudi proxies are already at war across the Middle East. Syrian President Bashar al-Assad, a close Iranian ally, has received money and weapons from Tehran, which has also dispatched intelligence operatives and combat-hardened fighters from Lebanon’s Hezbollah militia to Assad’s aid. Meanwhile, Riyadh has funneled weapons, money and supplies to the loose-knit alliance of rebels fighting to unseat him. The outside support keeps the country’s brutal civil war chugging along, with hundreds of thousands dead, millions displaced, ancient cities such as Aleppo largely obliterated and neither side closer to a final victory.

In Lebanon, Iran has built Hezbollah into the strongest paramilitary force in the region, one capable of repeatedly beating back the mighty Israeli army. Hezbollah is also the most powerful political party in Lebanon, where it holds veto power over the country’s fragile, pro-Western, Sunni-led central government. Riyadh, hoping to prop up Lebanon’s official military as a bulwark to Iran, announced last year that it was giving that force an eye-popping $3 billion grant, nearly double its annual $1.7 billion budget. Beirut’s troops aren’t nearly as well-equipped or well-trained as Hezbollah’s, but the Saudi money will help narrow that gap. Iran responded with an aid offer of its own, pledging to give the Lebanese military — and, significantly, Hezbollah — ammunition, mortars, anti-tank missiles and other light weaponry.

Elsewhere, Bahrain’s government believes that Iran is fomenting unrest among the country’s Shiite majority in an attempt to force regime change in the oil-rich Sunni monarchy. Saudi Arabia deployed troops there in 2011 to help quell a Shiite uprising.

Wealthy Saudi Arabia has a military bristling with high-tech, American-made weapons. But Saudi leaders worry that they are losing the long and bitter rivalry with Tehran, according to regional diplomats. They look across their northern border with Iraq and see a Shiite government so closely linked to Iran that it is depending on the Islamic republic’s weapons, fighters and support to help defeat the Islamic State. The Saudis look across their southern border with Yemen and see a nation under the control of Iran-allied insurgents.

The Saudis are even more spooked by the Obama administration’s nuclear talks with Iran, which they — like Israel and the other Persian Gulf monarchies — believe to be a historic mistake that will leave Iran’s nuclear program largely intact and its economy unshackled by Western sanctions. Privately, Saudi officials make little attempt to hide their disdain for President Obama, whom they deride as naive and indecisive.

Publicly, the kingdom hints that it may seek its own nuclear bomb to counter a nuclear-armed Iran. Pressed about the country’s nuclear plans on CNN on Thursday, the Saudi ambassador to the United States, Adel al-Jubeir, said that “the kingdom of Saudi Arabia will take whatever measures are necessary in order to protect its security.” Jubeir also blasted Tehran for its “interference . . . in the affairs of other countries in the region, whether it’s Iraq, Syria, Lebanon, Yemen and other parts.”

Against that backdrop of fear and violence, Saudi Arabia has assembled a broad coalition of Sunni Arab powers for what could be a sustained and expansive campaign against Yemen’s Houthis and, by extension, Iran. Cairo has sent warships to the Gulf of Aden, and Egypt’s leaders may send ground troops as well. Jordan and virtually all of Saudi Arabia’s neighbors have joined the operation and even Sudan has promised ground forces. Yemen’s ousted leader, meanwhile, has taken refuge in Riyadh after ignominiously fleeing his country by boat as Houthis closed in on the port city he’d called home after being pushed out of Sanaa, Yemen’s capital.

Iran has stayed mostly quiet since the start of what Saudi Arabia has grandiosely named Operation Storm of Resolve, but Tehran — which denies supporting the Houthis — let the mask slip a little during a speech last month by President Hassan Rouhani. Rouhani said his country was helping the rebels as part of a broader push against a rising tide of Sunni extremists such as the Islamic State. “You can see that the power that was able to help the people of Iraq, Syria, Lebanon and Yemen against terrorist group[s] is the Islamic Republic of Iran,” he said.

As the fighting intensifies, Iran and Saudi Arabia have at least one bit of common ground: shared antipathy toward al-Qaeda’s Yemen affiliate, which is widely seen as the most dangerous terrorist group in the world because of its bombmaking expertise and its ability to get operatives into the West. (The group attempted to down a U.S. airliner over Detroit on Christmas Day in 2009 and claimed responsibility for the Charlie Hebdo massacre in Paris.)

Al-Qaeda in the Arabian Peninsula (AQAP) has targeted both Saudi Arabia and Yemen’s Houthis. In October, an AQAP suicide bomber killed at least 42 people at a Houthi rally in Sanaa. In December, the group killed dozens more in a string of suicide attacks. It has released audio recordings promising to step up its fight against the “apostate” Houthis.

Saudi leaders, meanwhile, have a deeply personal reason to battle the group: In the summer of 2009, an AQAP operative detonated a bomb during a meeting with Prince Mohammed bin Nayef, then the kingdom’s deputy interior minister. The blast sheared the bomber in half but failed to kill Mohammed, who is now the country’s interior minister and deputy crown prince.

Nevertheless, the cliche about the enemy of your enemy being your friend isn’t true with rivals that hate each other as much as Saudi Arabia and Iran do. The two nations may be willing to do their part in the fight against AQAP, but that is likely to be the only good news out of Yemen for quite some time.

Twitter: @yochidreazen

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