"We had nothing to do with the strike last night," Mattis told reporters.
On Monday night, the Syrian government army in the provinces of Aleppo and Hama was subjected to a missile attack. According to some reports, ammunition depots were attacked. A number of media outlets reported the deaths of more than 26 Shiite fighters under the leadership of the Iranian Islamic Revolutionary Guard Corps (IRGC).
READ MORE: WATCH: Video of Alleged Missile Strike on Syrian Military Bases in Hama
However, the Iranian Tasnim news agency, citing an unnamed source, has denied the fact of missiles hitting Iran's base in Syria, saying that "all these reports over attack on an Iranian military base in Syria and the martyrdom of several Iranian military advisers in Syria are baseless."
Speaking to Sputnik, a spokeswoman for the Israeli Defense Forces, however, has declined to comment on missile strikes against several Syrian government military bases.
There have been no official statements from the Syrian government on the incident yet. It is also not known yet who struck at the Syrian army's warehouses.