Iran threatened that a reported Israeli strike in Syria would have “grave consequences for Tel Aviv” on Thursday, days after saying that an attack on Syria would be seen as an attack on Iran.

Syria added that the attacks “would not go unanswered.”

On Wednesday, Damascus said Israeli planes struck a “research facility” northwest of the Syrian capital. The accusation came after reports from foreign news sources earlier in the day saying Israel hit a weapons convoy near the Syria-Lebanon border that was transferring arms to the terror group Hezbollah.

“The Israeli regime’s strike on Syria will have serious consequences for Tel Aviv,” one of Tehran’s deputy foreign ministers was quoted by the semi-official PressTV network as saying.

Iran is a major backer of both Syrian President Bashar Assad and Lebanon-based Hezbollah.

Iran’s Foreign Minister Ali Akbar Salehi condemned the airstrike on state television, calling it a clear violation of Syria’s sovereignty. His statement echoed similar condemnations from Russia, the Arab League and Hezbollah.

Last week, Iran warned the West against intervening in the ongoing civil war in Syria, with top adviser Ali Akbar Velayati saying that “an attack on Syria is considered an attack on Iran and Iran’s allies.”

Syrian officials also said they would not stay quiet after the attack.

“All options for a response against Israeli aggression are open,” an official close to the Assad regime said, according to Syrian press reports. “The Zionists are trying to use the situations in Syria to restart the crisis when the government was managing to work toward a diplomatic solution.”

The Syrian ambassador to Lebanon Ali Abdel Karim said Israel, the Americans and the Arab regimes who took their side “know Syria will defend its sovereignty and land.”

Damascus “is capable of executing a surprise response to the attack on the science research center in Jamariah,” Karim told reporters in Beirut.

The site targeted by Israel was the target of multiple attacks by those objecting Assad’s rule over the past two years, Karim added.

The Syrian Foreign Ministry summoned Major-General Iqbal Singh Singha, the head of mission and force commander for United Nations Disengagement Observer Force on the Golan Heights, to complain about the Israeli violation.

The force was established in 1974 following the disengagement of Israeli and Syrian forces in the area and has remained there since to maintain the cease-fire. Israel captured the Golan, a strategic plateau, from Syria in the 1967 Middle East war.

The Jamraya research center is in the town of Jamraya, 20 kilometers east of the Lebanese border, surrounded by army bases.

Diplomats in the Middle East familiar with Jamraya told Reuters that it a crucial element of Syria’s missile program, and that it is also home to a chemical weapons facility.

People who visited Jamraya recently told reporters it is surrounded by high walls and guarded by plain-clothed agents.

Asked about rebel attacks in the area, they said there had been some attempts to target the tanks with mortars but were not aware of any rebel activity in the last few days.

Israel has declined to comment on the reports of the strikes. Officials have said in the past that it would act to keep chemical weapons or other arms from being transfered to Hezbollah.

Vice Prime Minister Silvan Shalom said Sunday that any transfer of arms to Hezbollah “would be crossing a line that would demand a different approach.”

Maj. Gen. Abdul-Aziz Jassem al-Shallal, who became in December one of the most senior Syrian army officers to defect, told The Associated Press by telephone from Turkey that the targeted site near Damascus is a “major and well-known” center of weapons development known as the Scientific Research Center.

Al-Shallal, who until his defection was the commander of the Military Police, said no chemical or unconventional weapons were at the site. He added that foreign experts, including Russians and Iranians, are usually at such centers.

On Wednesday, reports surfaced that Israel’s air force carried out a number of sorties around the Lebanese-Syrian border on Tuesday and Wednesday. The target was reportedly a convoy carrying advanced weaponry to Hezbollah.

Regional security officials said Wednesday the shipment included sophisticated Russian-made SA-17 anti-aircraft missiles, which if acquired by Hezbollah would enable the militants to shoot down Israeli jets, helicopters and surveillance drones. The officials spoke on condition of anonymity because they were not authorized to brief the media.

A Western official told The Wall Street Journal that the two reports may not be mutually exclusive.

Russia, Syria’s strongest international ally, said Moscow is taking “urgent measures to clarify the situation in all its details.”

“If this information is confirmed, we have a case of unprovoked attacks on targets in the territory of a sovereign state, which grossly violates the U.N. Charter and is unacceptable,” Russia’s foreign ministry said in a statement. “Whatever the motives, this is not justified.”

Earlier Thursday, Hezbollah condemned the attack, claiming that it was intended to stunt “Arab and Islamic technological development.”

“In line with its inherent spirit of aggression and criminality, and in accordance with its policy of preventing any Arab or Islamic power from developing technological and military capabilities, Israel perpetrated a barbaric attack against a Syrian installation for scientific research on Syrian territory, causing the death of a number of Syrians, the injury of others, and the destruction of the installation,” the statement read.

Lebanon and the Arab League slammed Israel for the attacks, calling them a violation of the countries’ sovereignty.

Jerusalem has long feared that Syrian chemical weapons could be turned against Israel.

Earlier this week, Israel moved a battery of its new Iron Dome rocket defense system to the northern city of Haifa, which was battered by Hezbollah rocket fire in the 2006 Israel-Hezbollah war. The Israeli army called that move “routine.”

Israel Military Intelligence Chief Aviv Kochavi is in Washington for consultations at the Pentagon, including meetings with Joint Chiefs of Staff head Martin Dempsey.

US officials told The New York Times on Wednesday that Israel notified the United States about the reported airstrike.

MK Tzachi Hanegbi, who is close to Prime Minister Benjamin Netanyahu, stopped short of confirming Israel’s involvement in the strike.

Hanegbi hinted, however, that Israel could carry out similar missions in the future. He said pinpoint strikes were not enough to counter the threat of Hezbollah obtaining sophisticated weaponry from Syria.

“Israel’s preference would be if a Western entity would control these weapons systems,” Hanegbi said. “But because it appears the world is not prepared to do what was done in Libya or other places, then Israel finds itself like it has many times in the past facing a dilemma that only it knows how to respond to,” he added.

He was referring to NATO’s 2011 military intervention in Libya that helped oust dictator Muammar Gaddafi.

“Even if there are reports about pinpoint operations, these are not significant solutions to the threat itself because we are talking about very substantial capabilities that could reach Hezbollah,” he added.