SYRIA-ISRAEL BORDER, Golan Heights — Ever since the Iranian Islamic Revolution in 1979, Iran and Israel have been fighting each other in the shadows — through proxies, assassination squads and cybervirus attacks, but never as rival armies meeting on the field of battle. That may be about to change, and if it does, it will have vast implications for the whole Middle East.

I’m sure neither side really wants a war. It could be devastating for Israel’s flourishing high-tech economy and for Iran’s already collapsing currency. But Iran’s Revolutionary Guards’ Quds Force seems determined to try to turn Syria into a base from which to pressure Israel, and Israel seems determined to prevent that. And in the past few weeks Israel and Iran have begun quietly trading blows directly in Syria.

Round 1 occurred on Feb. 10, when an Iranian drone launched by a Quds Force unit operating out of Syria was shot down after it penetrated northern Israel airspace.

Initial reports were that the drone was purely on a reconnaissance mission. But the Israeli army’s spokesman, Brig. Gen. Ronen Manelis, said that the flight path and Israel’s analysis of the drone indicated that “the aircraft was carrying explosives” and that its mission was “an act of sabotage in Israeli territory.”

If true, that suggests that the Quds Force was trying to launch an actual military strike on Israel.

In Round 2, on April 9, Israeli jets launched a missile strike on T4, the drone’s home base — directly targeting, for the first time, an Iranian facility and personnel in Syria. Seven Quds Force members were killed.

Iran’s government vowed to take revenge.

So now the whole neighborhood is holding its breath: Will there be a Round 3? Israeli defense officials let it be known that if the Iranians strike back, Israel may use the opportunity to mount a massive counterstrike on Iran’s entire military infrastructure in Syria. Iran plans to provide the missiles to Hezbollah in Lebanon.

These Israeli defense officials say there is zero chance Israel will make the same mistake it made in Lebanon — letting Hezbollah establish a large missile threat there — by letting Iran do so in Syria.

The Israeli government reportedly distributed maps to Israeli news organizations showing five Iranian-controlled bases in Syria. The message from Israel to the Quds Force was hard to miss: “Beware. We know exactly where to find you.”

Iran has legitimate security concerns in the Gulf; it faces a number of hostile, pro-American Sunni Arab powers trying to contain its influence and undermine its Islamic regime.

But what is Iran doing in Syria?

Tehran’s building of bases and missile factories in Syria, after having helped President Bashar Assad largely crush the uprising against him, appears to be a move by the Quds Force’s military mastermind Qassem Suleimani to extend Iran’s grip on key parts of the Sunni Arab world and advance his position at home in his struggle for power with Hassan Rouhani, Iran’s president. The Quds Force now more or less controls — through proxies — four Arab capitals: Damascus, Beirut, Baghdad and Sanaa.

Indeed, Iran has become the biggest “occupying power” in the Arab world today. But Suleimani may be overplaying his hand.

Even before the recent clashes, many average Iranians were asking: What is Iran doing spending billions of dollars fighting wars? That concern is surely one reason Iran has not retaliated — yet.

The Israeli airstrike on T4, along with the U.S.-British-French airstrike on the Syria, have actually exposed the strategic vulnerabilities of both Russia and Iran in Syria. Their forces are very powerful versus the rebels there, but not so powerful versus the Western forces and Israel. Iran, which has to depend largely on Syria’s air defense system, is particularly exposed to Israel’s air force.

Suleimani could opt to strike back at Israel through proxies, either in the Middle East or against Israeli targets globally. But he now has to think twice about that, both because his forces in Syria are exposed.

Their ambitions are big — to create a base to pressure Israel directly, to dominate the Arab states around them and to maintain the fervor of the Islamic Revolution. Everyone is basically awaiting Suleimani’s next move. Does he back down, lose a little face, and wait until he is stronger? Does Israel let him?

The status quo is not sustainable.

— Thomas Friedman is a columnist for The New York Times.