A late-night air strike targeting a base in the Syrian city of Hama was carried out by Israeli F-15s, US officials revealed on Tuesday amid calls for retaliation from Iran. Media outlets associated with the Syrian government and Hezbollah initially suggested Israel was behind the attack, but parties on both sides were slow to shed light on the strike.

The three US officials, cited by NBC News, said the strike targeted a base believed to house Iran’s 47th Brigade, along with recently delivered weapons including surface-to-air missiles. Reports on Monday indicated that most of the at least 26 killed in the strike were Iranians.

“On the list of the potentials for most likely live hostility around the world, the battle between Israel and Iran in Syria is at the top of the list right now,” one of the officials was quoted as saying.

A senior member of Iran’s parliament vowed on Tuesday that the country would retaliate against the “Israeli aggression,” according to reporting from Reuters. Iranian military and political leaders have been threatening in recent weeks that any further provocation would be met with a response, after a previous Israeli air strike that reportedly killed seven Iranians.

“We will respond to any aggression on Iran at the right time and place,” Alaeddin Boroujerdi, head of the parliament’s National Security and Foreign Policy committee, told a news conference after meeting with Syrian President Bashar al-Assad earlier this week.