According to a June 2015 Reuters report that cited "jihadist ideologues" as a source, 90% of ISIL's fighters in Iraq were Iraqi, and 70% of its fighters in Syria were Syrian. The article stated that the group had 40,000 fighters and 60,000 supporters across its two primary strongholds in Iraq and Syria. According to scholar Fawaz Gerges writing in "ISIS: A History", some "30 percent of the senior figures" in ISIL's military command were former army and police officers from the disbanded Iraqi security forces, turned towards Sunni Islamism and drawn to ISIL by the US de-Ba'athification policy following the US invasion of Iraq.