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(CNN) – The extremist Sunni militant group ISIS, which recently declared a caliphate in parts of Syria and Iraq, wrested control of a major Syrian oil field in a sweeping land grab Thursday, a UK-based monitoring group said.
"This is what I call al Qaeda version 6.0," said former U.S. Ambassador to Iraq Ryan Crocker. ISIS is "far bigger, far better organized, better funded, better equipped than the al Qaeda of 9/11."
While U.S. boots on the ground should be limited to advising, "we've reached the point where we need to be seriously considering and executing very carefully targeted air strikes against facilities that they hold, against their command and control nodes, and against they're leadership if we've got them in our sights," Crocker said in an interview with CNN's "The Lead with Jake Tapper."
That applies to both Syria and Iraq.
"The Islamic state may have done us a favor by publicly erasing the Iraqi-Syrian border. If they have, I think we should too, and go after their targets wherever they are," said Crocker.
The extremist group announced last week the establishment of a "caliphate," an Islamic state stretching across the region, and said it would now be known as the Islamic State, rather than the Islamic State of Iraq and Syria.
After close to 40 years working in the middle east, Crocker said he came away with two lessons: Be careful what you get into, and be even more careful what you get out of.
"Disengagement can have graver results than engagement in the first place," Crocker said, adding that in his view, the U.S. "didn't do either very well in Iraq."
"We still have time to help the Iraqis get back on a stable course, but we're going to have move quickly, and we're going to have to move with determination, and we're going to have to move both politically and militarily," said Crocker.
Crocker spent decades trying to make Iraq work. He said he has been making the case privately, and publicly, for U.S. engagement in the country for quite some time.
"I'm sorry it took such a major crisis, one that does threaten our national security, to bring about that engagement, but I'm glad that it's happened," said Crocker.