Looking at the Islamic State's string of military conquests in northern Iraq over the past week, one could think the jihadists outnumber their opponents 10 to 1.
After routing government forces in an onslaught launched on June 9, it has managed to hold Iraq's second city Mosul and gone on the offensive again last week, repeatedly ousting the much-celebrated Kurdish peshmerga on various fronts.
But the jihadist group remains a relatively small force and its strength lies not in numbers. Here are five reasons identified by military experts for its military successes:
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Newly acquired weapons
The Islamic State has made use of the military equipment it seized from its defeated enemies, including tanks, humvees, missiles and other heavy weaponry.
The amount of hardware, often US-made, the Iraqi army left behind in its spectacular retreat when the jihadists launched their offensive two months ago has transformed IS' capabilities.
"And they keep taking it, they made significant gains of the kind of equipment they needed the most," said Anthony Cordesman, from the Washington-based Center for Strategic and International Studies.
IS has long had a foothold in Iraq — that's even where the group's first incarnation was born in 2004 — but it became what it is today by fighting in neighbouring Syria.