<p>Islamic State militants have set fire to Iraq’s largest oil refinery, escalating tensions in the region and raising questions about how much control ISIS could potentially gain over the world’s oil supply.</p>
<p>This isn’t the first time this particular refinery has been attacked; it’s a favorite target of ISIS militants. They have attacked the refinery in the past as a way of securing fuel to smuggle to parties who fund their self-declared “caliphate” in northern Iraq and Syria.</p>