DHAKA: Fighters with the militant group the Islamic State in Iraq and Syria reached the triangle border between Iraq, Syria and Turkey, it said in a message posted on Twitter on Sunday.

ISIS took control of Iraq's largest hydroelectric dam on Iraq's Tigris River, which provides power to the city of Mosul about 50 kilometers (31 miles) to the south, the commander of the Peshmerga Kurdish fighters who had been defending the facility said Sunday.

The dam workers remained inside the facility, which fell after a 24-hour battle, Lt. Col. Herash said, reports CNN.

A "horrendous prospect"

ISIS -- known for killing dozens of people at a time, while carrying out public executions, crucifixions and other acts -- has taken over several cities as it seeks to create an Islamic caliphate that encompasses parts of Iraq and Syria.

Daniel Pipes, the president of the Middle East Forum, said seizing dams is a tactic the group uses to gain control of a town and its people.

No dam, however, is as formidable or as important to Iraq as the one in Mosul.

"If you control the Mosul Dam, you can threaten just about everybody," Pipes told CNN's Jonathan Mann.

Pipes said the militant group now has the potential to create a flood so massive and catastrophic that it would not only cause death, destruction and chaos locally in the city of Mosul, but more than 450 kilometers (280 miles) away in Baghdad as well.

"It's a horrendous prospect," he said.

Peshmerga Kurdish fighters also pulled out of the towns of Zumar and Wana after being surrounded by ISIS fighters and isolated from any support, Kurdistan Democratic Party regional official Ismat Rajab told CNN on Sunday.

BDST: 0952 HRS, Aug 4, 2014