In the last week alone, Israel has killed a senior Hamas militant in an airstrike in Beirut, Hezbollah has fired barrages of rockets into Israel, the U.S. has killed a militia commander in Baghdad and Iran-backed rebels in Yemen have traded fire with the American Navy.

Each strike and counterstrike increases the risk of the already catastrophic war in Gaza spilling across the region. And in the decades-old standoff pitting the U.S. and Israel against Iran and allied militant groups, there are fears that any one party could trigger a wider war if only to avoid appearing weak.

The divisions within each camp add another layer of volatility: Hamas might have hoped its Oct. 7 attack would drag its allies into a wider war with Israel. Israelis increasingly talk about the need to change the equation in Lebanon, even as the U.S. aims to contain the conflict.

As the intertwined chess games grow ever more complicated, the potential for miscalculation rises.

Gaza is ground zero

Hamas says the Oct. 7 attack that triggered the war in Gaza was an act of purely Palestinian resistance to Israel’s decades-long domination of the Palestinians. There is no evidence that Iran, Hezbollah or other allied groups played a direct role or even knew about it beforehand.

But when Israel responded by launching one of the 21st century’s most devastating military campaigns in Gaza, a besieged enclave home to 2.3 million Palestinians, the so-called Axis of Resistance - Iran and the militant groups it supports across the region - faced pressure to respond.

The Palestinian cause has deep resonance across the region, and leaving Hamas alone to face Israel’s fury would have risked unraveling a military alliance that Iran has been building up since the 1979 Islamic Revolution put it on a collision course with the West.

Hezbollah threads the needle

Of all Iran’s regional proxies, Hezbollah faces the biggest dilemma.

If it tolerates Israeli attacks, like the strike in Beirut that killed Hamas’ deputy political leader, it risks appearing to be a weak or unreliable ally. But if it triggers a full war, Israel has threatened to wreak massive destruction on Lebanon, which is already mired in a severe economic crisis. Even Hezbollah’s supporters may see that as too heavy a price to pay for a Palestinian ally.

Hezbollah has carried out strikes along the border nearly every day since the war in Gaza broke out, with the apparent aim of tying down some Israeli troops. Israel has returned fire, but each side appears to be carefully calibrating its actions to limit the intensity.

A Hezbollah barrage of at least 40 rockets fired at an Israeli military base on Saturday sent a message without starting a war. Would 80 have been a step too far? What if someone had been killed? How many casualties would warrant a full-blown offensive? The grim math provides no clear answers.

And in the end, experts say, it might not be a single strike that does it.

US deterrence only goes so far

The U.S. positioned two aircraft carrier strike groups in the region in October. One is returning home but being replaced by other warships. The deployments sent an unmistakable warning to Iran and its allies against widening the conflict, but not all of them seem to have gotten the message.

Iran-backed militant groups in Syria and Iraq have launched dozens of rocket attacks on U.S. bases. The Iran-backed Houthi rebels in Yemen have attacked international shipping in the Red Sea, with potential consequences for the world economy. Iran says its allies act on their own and not on orders from Tehran.

The last thing most Americans want after two decades of costly campaigns in Iraq and Afghanistan is another war in the Middle East.

How does this end?

The regional tensions are likely to remain high as long as Israel keeps up its offensive in Gaza, which it says is aimed at crushing Hamas. Many wonder if that’s even possible, given the group’s deep roots in Palestinian society, and Israel’s own leaders say it will take many more months.

The U.S., which has provided crucial military and diplomatic support for Israel’s offensive, is widely seen as the only power capable of ending it. Iran’s allies seem to believe Washington will step in if its own costs get too high - hence the attacks on U.S. bases and international shipping.

U.S. Secretary of State Antony Blinken, the European Union’s top diplomat, Josep Borrell, and German Foreign Minister Annalena Baerbock are all back in the region this week, with the aim of trying to contain the violence through diplomacy.

But the most important messages will still likely be sent by rocket.

“The Americans do not want an open war with Iran, and the Iranians do not want an open war with the United States,” said Ali Hamadeh, an analyst who writes for Lebanon’s An-Nahar newspaper. “Therefore, there are negotiations by fire.”