Syria said Israeli jets attacked several military sites near the capital Damascus and the central city of Homs early Monday, killing four civilians, including an infant.

The Syrian Observatory for Human Rights, a Britain-based war monitor, said Israel launched strikes both from the air and sea, targeting Iranian-linked bases near Homs and at least 10 targets near Damascus, including a base where Iran’s Islamic Revolutionary Guard Corps forces are headquartered and a weapons research center.

Israel did not comment on the attack — one of the most extensive series of strikes in several months, coming less than a week after a trilateral summit with Russia and the United States concerning Tehran’s activities and military presence in the region.

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Syria’s official mouthpiece said four civilians, among them a month-old baby, were killed and 21 people injured in explosions in Sahnaya, a neighborhood of Damascus. It blamed the deaths on “Zionist aggression.”

Other news sites in the country reported at least 50 people injured in the strikes.

While hundreds of casualties have been linked to Israeli strikes in Syria — mostly Syrian soldiers, Iranian troops and other foreign nationals connected to pro-Iranian militias — it is exceedingly rare for civilians to be said injured in these attacks.

State news agency SANA said that Syrian air defense had intercepted several of the incoming missiles that were fired from Lebanese airspace.

A projectile, later identified as a Syrian surface-to-air missile, crashed into a forest in northern Cyprus during the predawn exchange, sparking a large fire.

SANA gave no further details on the sites targeted.

However, the Observatory for Human Rights said the strikes targeted a research center and a military airport west of the city of Homs, where the Shiite Hezbollah terror group and Iranian forces are deployed.

Rami Abdel Rahman, the observatory chief, said the strikes injured some of those pro-Iranian troops.

In the Damascus area, the monitor said strikes targeted the 91st Brigade base where the IRGC were headquartered and a research facility in Jamraya.

Jamraya, which lies just over 10 kilometers (seven miles) northwest of Damascus, is home to several military positions and a branch of the Syrian Scientific Studies and Research Center (SSRC).

The US has repeatedly imposed sanctions on the SSRC for its alleged role in chemical weapons production. France has also imposed sanctions on the agency.

Israeli airstrikes reportedly hit the facility in May 2013 and again in February 2018.

The monitor said that at some sites large blasts were caused by exploding ammunition depots and noted lots of ambulances had headed to the sites.

There was no response from the Israel Defense Forces, which rarely comments on reported strikes.

The Israeli military has acknowledged carrying out hundreds of airstrikes in Syria in recent years on targets linked to Iran, which is backing President Bashar Assad’s regime in the Syrian civil war.

The reported strikes came just hours after an Israeli satellite imagery analysis company said Syria’s entire S-300 air defense system appeared to be operational, indicating a greater threat to Israel’s ability to conduct airstrikes against Iranian and pro-Iranian forces in the country.

Until now, only three of the country’s four surface-to-air missile launchers had been seen fully erected at the Masyaf base in northwestern Syria.

Israel has threatened to destroy the S-300 system if it is used against its fighter jets, regardless of the potential blowback from Russia.