As you might imagine by their name, the Islamic State of Iraq and Syria (ISIS) is a problem for the governments of both Iraq and Syria, and the governments are said to be working together in retaliation.
Other rebel factions have reported increased Syrian air force activity over the past 24 hours, focusing on ISIS bases in Raqqa Province and Hasakeh, with Iraq providing them intelligence on targets. Raqqa is seen as ISIS de facto capital.
Rebel mouthpiece the Syrian Observatory for Human Rights has reported that ISIS has brought heavy weapons, including seized tanks, into Syria’s northeast from Iraq. The weapons were apparently taken after the Iraqi troops fled from several bases.
Iraq’s Maliki government hasn’t had the best of relations with Syria over the years, but seems to be willing to consider any ally it can get as ISIS takes over much of their west. It is unclear how much help Syria can really be at this point, however, as it is in the middle of its own civil war, with ISIS already having taken large chunks of their country as well.