"They're using American humvees as vehicle-borne improvised explosive devices to run up against the peshmerga lines. The Kurds have nothing to stop them -- just bullets," retired Army Lt. Gen. Michael Barbero, a former deputy commander of U.S. forces in Iraq, told ABC News.
Among the jihadis featured in the killer tourism video is a grinning Finnish fighter, who pledges that the caliphate "will expand to the whole world by Allah's permission," and that ISIS is "calling on all the Muslims living in the West, America, Europe and everything else to come."
"And here you go for fighting and afterwards you come back to your families. And if you get killed then you'll enter Jannah [paradise], insha'allah [Godwilling], and Allah will take care of the ones you've left behind," the fighter, identified as Abu Shuaib as-Somali, says.
The recent shift to putting westerners on camera, whose value previously has been their anonymity and potential ease of travel between Syria, Iraq and their home countries, may be an implied threat to western countries contemplating attacks on ISIS, said Robin Simcox, a terrorism researcher at the Henry Jackson Society in London.
Applying for Terror: Group Wants ‘Character References’
But ISIS also faces competition in its recruitment of westerners with their skills and passports from their weakened rival in the Syrian resistance, Jabhat al-Nusra, which is core al Qaeda's endorsed affiliate.
"Some people argue they're competing to attack the west. There clearly will be competition to recruit westerners," said Peter Neumann, a King's College researcher in London who directs field research which includes interviews of foreign fighters. Most of the westerners have joined ISIS, he said.
"A lot of westerners want to join Jabhat al-Nusra but are turned down, we've heard," Neumann told ABC News this week. "Jabhat al-Nusra has been much more selective about recruiting western fighters. They even want character references."
A 22-year-old Florida man, Moner Mohammad Abu-Salha, appeared posthumously in Jabhat al-Nusra videos posted online in late July, two months after U.S. officials confirmed he drove an armored truck bomb that detonated inside a Syrian regime military camp. He also traveled home to Florida before returning to Syria, officials say.
"We need to come and fight...whether you be in America, Britain, any place in the world right now," Abu-Salha said in a rambling half-hour video in which he praised slain Yemeni-American AQAP terror leader Anwar al-Awlaki and also warned President Obama that his days are numbered.
"The key thing they bring is their passport. If ISIS is looking to carry out attacks in the west and Europe, the western passports are very valuable. Not just sending people back to carry out attacks, but also to recruit others," Simcox said.
The jihadis in the ISIS video repeatedly reject the western life they grew up in and encourage those similalrly disaffected to journey to "al Sham."
"I don't think there's anything better than living in the land of Khilafah," said a British fighter calling himself Abu Abdullah al-Habashi. "You're not living under oppression."