Israel teetered on the brink of a long-anticipated war along its northern border for a few hours Saturday, Feb. 10, but even though most of the destruction involved Israel and Syria, no one should have any doubts about the real source of the trouble: Iran.

It was Iran that, for reasons unknown, chose to fly a drone from Syria into Israeli airspace and started the temporary tempest. Israel not only shot down the drone, but also launched strikes against the suspected Iranian command-and-control center operating the plane from southern Syria.

The Syrians, whether feeling protective of their Iranian allies or just itching for an excuse to target the Israeli air force after it conducted thousands of reconnaissance missions and a few airstrikes in Syria during its seven-year civil war, launched a barrage of anti-aircraft fire at the Israeli planes. One F-16I fighter-bomber was shot down and crashed in northern Israel, injuring the pilot and navigator.

Israel quickly recovered from the shock of having its sense of air supremacy deflated and launched attacks directly on Syrian air defenses. An Israeli military spokesman estimated that within an hour of the F-16 crash, Syria lost one-third to one-half of its air defense system.

Cartoon by Yaakov Kirschen, Dry Bones

Fortunately, all sides seemed to accept a rapid de-escalation. Syrian leader Bashar Assad still has more than enough internal fighting to keep him busy, and Israel’s strikes after the F-16 was shot down served as a reminder that a war with his more powerful rival could damage his prospects of remining in power. Russia, whose military presence in the Middle East is a long-term problem, possibly was beneficial in this instance because it maintains instant communication with both militaries and has the power to compel them to settle down.

But Syria isn’t a real threat to Israel, which has shown it has the military and intelligence assets to handle Assad and whatever other internal power might arise there. Iran, however, is another story.

Iran has tens of thousands of troops in Syria, along with allied militias, and the use of the drone Feb. 10 may indicate an increasing willingness to open a military front on Israel’s border. Any fighting south from Syria by Iran would no doubt be coordinated with attacks from Lebanon by the Iranian-funded Hezbollah, which is believed to have stockpiled 150,000 missiles and rockets since battling Israel to a stalemate in 2006.

It hasn’t found an excuse to launch those missile at Israel — yet.

One of the ironies of the 2015 Iran nuclear deal is that an agreement defended by President Barack Obama as the only alternative to an Israeli-Iranian war could be making such a war more likely.

The $100 billion or so the deal freed up for Iran has enabled it to become more aggressive around the Middle East, including its support for Hezbollah and its own deployment of troops in Syria. The Iranian regime’s failure to spend that money at home to improve living conditions has powered domestic unrest that also provides motivation to engage in a war that could unite the nation in patriotic fervor.

It’s therefore crucial for the United States to keep stating its full support for Israel’s right to self-defense and to make clear that Iran will face fresh sanctions if it goes to war against the closest U.S. ally in the region.