The heavily militarized, politically divided island of Cyprus — one more problem the United Nations won’t solve this week — is already girding for an influx of British and other evacuees from Lebanon as that husk of a country endures more Israeli airstrikes in response to Hezbollah’s attacks on Israel. That is to be expected, but due east is where far darker clouds are gathering: Syria. 

In that benighted land, beholden like Beirut to Tehran, there is already a human drama unfolding as people attempt to flee from the turmoil in Lebanon. On Wednesday, UN officials estimated that thousands of Lebanese as well as Syrian families who had previously fled Syria’s civil war had made the journey into Syria. They aren’t the only ones. 

According to a new report in the Saudi magazine Al Majalla, an unspecified number of Houthis may already be Syria, primed to launch attacks against Israel from the north. While the Houthis are an Iranian-backed group based in Yemen, an earlier report from i24news suggested that fighters are finding their way to Syria via Iraq and coming to the area that borders the Golan Heights. This is according to a Syrian source “a prelude to a new phase of escalation against Israel.” 

It is not like the Iran-backed Hezbollah, with its arsenal of tens of thousands of missiles still mostly intact as the launch of a large one toward Tel Aviv on Wednesday indicated, needs Houthi reinforcement for further attacks against Israel.  Neither is it inconceivable that Iran could be threading more than one needle at the same time.

Iran’s foothold in Syria is no secret. According to the Syrian Observatory for Human Rights, there are more than 65,000 pro-Iranian militia fighters in regions of Syria still under the control of Bashar Al-Assad. Nearly a third of the country is not under his control. That number, though, could in reality be closer to 100,000. 

Right now Mr. Al-Assad is treading a careful line, as evidenced by his near-total silence on the dramatic events unfolding less than 50 miles from Damascus. There are different reasons for that. The Syrian dictator is less smooth operator than survivor in the toughest of neighborhoods.

Weakened by the long years of civil war, he does not possess the means to engage in nearby conflicts directly. Were he to contemplate that nonetheless, he knows that doing so would render him even more vulnerable to Israeli counterattack than he already is. 

Jerusalem has seldom hesitated to bomb Iranian installations in Syria or to eliminate figures of the Islamic Republic and its regional allies who have turned up in the fractured desert dictatorship.

At the same time, while European foreigners and well-heeled Lebanese may eye Cyprus as their escape hatch if things blow up, Syria is itself a potential exit route from the chaos — not just for Lebanese civilians, but for Hezbollah terrorists and other Iranian-allied brigands in the region. 

While Syria and Hezbollah are united in their enmity toward Israel, the relationship is complex. When Syria wobbled under the pressure of civil strife a decade ago, Hezbollah’s chief, Hassan Nasrallah, wasted little  time in dispatching some of his best men to help shore up the regime. 

Now that Mr. Nasrallah has tied Hezbollah’s fate to that of Hamas in Gaza, however, old fault lines are being exposed. Mr. al-Assad’s coolness toward Hamas and the Gaza situation in general is at least partly derived from what Damascus saw as Hamas’s support of the Syrian uprising in its early days.  In the Middle East as elsewhere, revenge is sometimes a dish best served cold. 

The Syrian Observatory for Human Rights has stated that the Lebanese making a beeline for Syria have mainly found refuge in the city of al-Qusayr, situated in the province of Homs, as well as in localities in some regions of Damascus and Tartus that are said to be held by Hezbollah.

Lebanon and  Syria are each to no small degree client states of Iran, but their fates are linked in another important way. More than one million Syrian refugees who fled the Syrian civil war, which started in 2011, ended up in Lebanon. The refugee crisis in the region is what sparked the ongoing migrant crisis in Europe. 

So even if Syria sits out  or manages to dodge the current round of hostilities between Hezbollah and Israel, it is still a major contributor to the region’s instability. Syria’s geography is something of a curse — at least while the country is still led by a tyrant beholden to Tehran.