While the international media was transfixed by the crisis in North Korea this week, Israel did something provocative and potentially dangerous: It bombed a suspected Syrian chemical weapons factory. It’s a move that escalates Jerusalem’s quiet involvement in the Syrian civil war and that may heighten tensions with Iran.

Around 2:42 am local time on Thursday, Israeli jets attacked a Syrian military installation near the city of Masyaf that allegedly produces chemical weapons and advanced missiles. The Syrian Army said two soldiers died, while the Syrian Observatory for Human Rights, the UK-based monitoring organization that supports anti-government forces in the civil war, claims there were at least seven casualties.

In a statement, the Syrian military said there could be “serious repercussions of such acts of aggression on the security and stability of the region.”

The Israeli government didn’t comment on the operation. But it looks like it hit Syria to prevent Iranian ally Hezbollah — a Lebanese militant group that considers Israel an enemy — from acquiring precision-guided missiles to use against Israel.

And the strikes came just one day after the United Nations blamed Syrian forces for a chemical weapons attack in April. After that attack, President Donald Trump ordered 59 Tomahawk missiles on a Syrian military base but didn’t completely destroy it. Israel’s strikes, however, appear to have hit much harder. And it’s a very big deal that Syria still had a chemical weapons facility, given that it had earlier promised to give up all of those weapons.

But even though the facility was in Syrian territory, the real target of the strike was Iran.

That’s because Tehran has spent the past five years fighting to keep Assad in power while taking advantage of the civil war’s chaos to gain more control in the region, in part by providing Hezbollah with advanced weapons. Israel, however, is willing to use military force to stop it from achieving those goals — and that could lead to problems down the road.

“This is something Israel cannot accept”

There’s little doubt that Israel is trying to send a message to Iran and Hezbollah.

“Iran is busy turning Syria into a base of military entrenchment,” Benjamin Netanyahu, Israel’s prime minister, said at a news conference last week. “It wants to use Syria and Lebanon as war fronts against its declared goal to eradicate Israel.”

“This is something Israel cannot accept,” he continued.

That line of argument has been used by other senior members of the Israeli government.

“Everything will be done to prevent the existence of a Shiite corridor from Tehran to Damascus,” Israeli Defense Minister Avigdor Lieberman said during a radio interview on Thursday.

Israel has launched around 100 strikes inside Syria over the past five years, according to Amir Eshel, a former chief of the Israeli Air Force. Usual targets include convoys of Syrian military or Hezbollah members. But Yaakov Amidror, a former Israeli national security adviser, told reporters in a conference call that Thursday’s airstrikes went further than other attacks because it targeted the chemical weapons center.

Israel is particularly worried about Hezbollah because they fought each other before. In 2006, they battled in a month-long war where the militant group fired more than 4,000 rockets into Israel, and Israeli forces fired around 7,000 bombs and missiles into Lebanon. About 160 Israelis troops and civilians died, according to the Israel Ministry of Foreign Affairs, and about 1,100 Lebanese — most of them civilians — perished, per the Human Rights Watch, a US-headquartered advocacy organization. It also reports about 4,400 Lebanese were injured, and around 1 million people were displaced.

Today, Israel believes Hezbollah has around 150,000 rockets at its disposal. But those weapons aren’t as advanced as the precision weapons made at the facility Israel struck. If Hezbollah acquired them, then it could more effectively damage Israel in a future war.

It’s worth noting the timing of the strikes. On Wednesday, a UN commission said Syria was responsible for killing around 80 people with chemical weapons in the town of Khan Sheikhoun. Assad denies his government had anything to do with the attack. In 2013, Syria promised to give up his chemical weapons as part of a diplomatic deal with Russia and the United States to avert a planned American strike that would have been in response to Assad gassing almost 1,000 of his own citizens to death near Damascus.

“The factory that was targeted in Masyaf produces the chemical weapons and barrel bombs that have killed thousands of Syrian civilians,” Amos Yadlin, a former head of Israeli intelligence, tweeted on September 7.

Hezbollah and Assad-backed forces have yet to strike back after Israeli attacks in Syria. As the New York Times notes, that’s likely because they prefer to focus on winning the civil war rather than on another fight with Israel.

But that could change. “Now it’s important to keep the escalation in check and to prepare for a Syrian-Iranian-Hezbollah response and even opposition from Russia,” Yadlin tweeted.

So far, at least, Syria and Hezbollah haven’t hit back.