A new study of last summer's Sarin attacks in Syria does not conclude who was responsible but raises the possibility that the White House's assertion that the rockets had been launched from areas solidly controlled by the Assad government cannot be proved, The New York Times reported Saturday.

The projectiles were probably fired from more than one Grad rocket launcher and had a range of about 1.8 miles, according to the study. Both sides in the civil war have the Russian-designed Grad.

The attacks are believed to have caused hundreds of civilian deaths. The Obama administration blamed the Assad regime and initially threatened military retaliation. In mid-September the U.S. and Russia reached agreement to dismantle Syria's chemical weapons.

The latest analysis was carried out by Massachusetts Institute of Technology Professor Theodore Postol and Richard Lloyd, an analyst for Tesla Laboratories, a military contractor.

Postol said the new analysis undermined the impression given by the White House that "satellite detections corroborate that attacks from a regime-controlled area struck neighborhoods where the chemical attacks reportedly occurred."

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According to Postol, "It is clear that if the U.S. government's claims that the allegedly observed launches came from 'the heart' of Syrian government controlled areas, there is a serious discrepancy between the meaning of this claim, the technical intelligence it relies on, and the technical properties of this munition."

Lloyd and Postol did not have access to the actual components of the rockets for their study.

The two experts say that warheads used in the attacks contained over 13 gallons of sarin.

In November, analyst Dan Kaszeta, a former officer in the US Army Chemical Corps, outlined the complexity of producing even small amounts of Sarin and concluded that it was likely the Syrian regime— not the insurgency— was responsible.

Allegations were raised starting in 2012 and into the summer of 2013 that poison gas had been used on multiple occasions during the Syrian civil war, according to the Arms Control Association.

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