The Islamic State of Iraq and the Levant (ISIS) continues to roll forward, adding to its collection of captured resources the Al-Omar Oil Field, the largest oil field in Syria located in the eastern Deir al-Zour province of the war-torn country, near the Iraqi border.

The Islamist group has already amassed great assets during its blitz offensive in Iraq, seizing Iraq’s largest oil refinery, a chemical weapons facility, and becoming the “world’s richest terrorist organization” by looting 500 billion Iraqi dinars ($425 million) from banks in Mosul.

Now, video footage uploaded to YouTube shows armed ISIS jihadists at the entrance to the field with their flag flying high, after having wrestled the field away from the Al-Nusra Front, a rival opposition force in Syria that is linked with Al-Qaeda, which ISIS broke off from.

The International Business Times reports that while it remains unclear if the field is fully operational and how much oil it is producing, before the war Syria was exporting 370,000 barrels a day.

ISIS’s lightning series of victories have given it control of a corridor on the Euphrates River ranging from the far-eastern Syrian town of Bukamal, located on the border with Iraq, on through the provincial capital of Deir al-Zour to the northwest from the border.

Additionally ISIS, which on Sunday declared itself an Islamic “caliphate” and proclaimed its leader Abu Bakr al-Baghdadi as “Caliph,” has succeeding in winning pledges of alleigance by numerous rebel factions in the area.

Among those factions are clans in Sheheil, an Al-Nusra Front stronghold for the moment, and nearby Ishara village.

ISIS’s rapidly expanding control has put Israel in its sights as well; video this week revealed that ISIS has transferred seized weaponry from Iraq into Syria, including long-range Scud missiles, which ISIS members threatened were “heading towards Israel.”