The Islamic State in Iraq and Syria cannot be defeated unless the United States or its allies take on the Sunni militancy in Syria, the chairman of the Joint Chiefs of Staff said Thursday afternoon.

“This is an organization that has an apocalyptic end-of-days strategic vision that will eventually have to be defeated,” the chairman, Gen. Martin Dempsey, said in his most expansive public remarks on the crisis since American airstrikes began in Iraq. “Can they be defeated without addressing that part of the organization that resides in Syria? The answer is no.”…

“You can hit ISIS on one side of a border that essentially no longer exists, and it will scurry across, as it may have already,” said Brian Katulis, a national security expert with the Center for American Progress, a Washington think tank with close ties to the White House…

According to an American intelligence estimate, ISIS could not be easily defeated by killing its top leadership. Given its decentralized command and control, experienced militants could easily replenish its upper ranks, American officials said.

Let’s be honest. The United States has crossed the threshold on Iraq. We’re in it to salvage the country — again — using American military might.

But the mission has also, very quickly, grown much bigger in less than two weeks. U.S. warplanes are no longer simply helping create escape routes for the Yazidis or protecting American personnel in Irbil in Iraqi Kurdistan. The U.S. is now directly taking on the world’s most militant extremist group, bombing its positions at the Mosul dam and beyond.

And it’s probably only the beginning…

Given the human heartache and political headache from the last Iraq intervention, not to mention the mess left behind, Washington needs to be honest upfront in answering basic questions. I’ve spent decades on the ground and in the minutiae of the Middle East, including Iraq, and I can’t yet discern the specifics of Washington’s intentions.

Iraqi officials have given their American counterparts clear signals that Baghdad is willing to let U.S. fighter jets operate out of Iraqi air bases, a move that would allow planes to stay airborne longer and deliver more strikes. But the Obama administration, at least for now, doesn’t seem all that interested…

At issue is a little-noticed aspect of this air campaign: None of the strikes against Islamic State targets inside Iraq have been carried out by U.S. aircraft based inside Iraq. Since the bombs began falling, U.S. aircraft have carried out more than 84 strikes. F-18s taking off from the aircraft carrier George H.W. Bush, which is in the North Arabian Sea, conducted more than a third of those strikes. The remainder were carried out by U.S. aircraft assigned to bases inside Qatar and other nearby countries…

To be sure, setting up American air operations at an Iraqi base would be a difficult undertaking, and would require the Obama administration to make a much bigger commitment to the effort in Iraq. The massive Baghdad International Airport is likely too crowded to use. The sprawling Al Asad facility in western Iraq is seen as one of the likeliest homes for any U.S. aircraft. But the Pentagon would have to assign hundreds of maintenance personnel there, as well as security for the American pilots, support crews, and planes themselves. Even though such troops could technically operate inside the base and still not be considered “combat boots on the ground,” it’s likely that such a move would only come if the administration was willing to sign off on an expanded U.S. mission with no clear end date, the military official said.

Judeh offers a clear-eyed depiction of the situation on the ground. While explicitly opposing partition of these two countries he notes that in fact, they both have been divided up by circumstances and demographics in a similar way. “In Syria, from the north, down along the Mediterranean coast and all the way to the south you have what you might call Regime-istan. It is controlled by Assad and extends to the Golan Heights because he feels it is convenient to maintain the possibility of provoking or confronting Israel. In the northeast you have an area controlled by Kurds, a Kurdistan. And then in the south you have Sunni-stan, which itself is divided, partially controlled by militants in the east and southeast into what you might call Extremist-stan.”…

Further, in a remarkable, as yet undocumented, not fully understood development, the mission against is the Islamic State is being undertaken by what might be called the Alliance Whose Name Must Not Be Spoken. It brings together — with a level of coordination that must be greater than anyone will publicly admit — the very strangest of battlefield bedfellows: the United States, the Kurds, the Iraqi regime, Iran, Russia, some NATO assistance, and Bashar al-Assad’s regime. It has the tacit support of everyone from Israel to (most of) the Gulf Cooperation Council. The perceived level of threat from IS has the grand mufti of Saudi Arabia characterizing it as “enemy number one of Islam.” More broadly, worldwide, countries like China, India, and the countries of the European Union recognize this threat. Setting aside the bizarre reality that the Iraqi government, put in place by the United States, is flying Russian-made planes in consultation with Iranian leaders with the support of the United States, the Peshmerga, and the Syrian air force, there is an opportunity for progress against this threat here.

The killing of James Foley has highlighted a tragic irony of the Obama administration’s decision to use military force against ISIS months after its rise to prominence in Syria. Advocates of such action have long warned that ISIS could pose a direct security threat to the United States if left unchecked. But these U.S. airstrikes may actually have made the group more likely to attack U.S. citizens and interests…

With the U.S. bombing its forces in Iraq, there’s no benefit for ISIS in refraining from attacks against Americans. And if Iraqi and Kurdish forces, with U.S. help, succeed in rolling back the group’s territorial gains, it may start to act more like a traditional al-Qaida affiliate—operating underground, using tactics like suicide bombings rather than open military confrontations, and striking both local and international targets…

Up until now, despite the escalating rhetoric, there’s been an uneasy peace between the U.S. and ISIS. Yes, the U.S. has provided some support to Syrian rebel groups fighting against the Islamic State, and ISIS has attacked the Iraqi government, a U.S. ally, but there had been little direct confrontation between the two. That’s obviously changed now, and while ISIS would certainly incur greater risk by engaging in a direct confrontation with the U.S. military, the Foley execution shows it does have some means to strike back.

None of this is to say that the U.S. shouldn’t attack ISIS. It may be true that the U.S. could no longer tolerate the long-term security threat from ISIS’s rise. But at least in the short term, it certainly seems like that threat has now increased.

Few of these Republicans have laid out what specifically they want Mr. Obama to do to intensify the battle. Mr. Schiff, who also is a member of the House Intelligence Committee, said there was a reason for that: as horrifying as Mr. Foley’s execution was, he said, it has not changed the reluctance of lawmakers to be drawn into a broader military engagement, especially one that requires sending American troops back into battle.

“Most Democrats and Republicans are extraordinarily wary of being sucked into a large occupation, both because it will kill a lot of Americans and because we saw in Iraq that it didn’t work,” he said.

Representative Peter Welch, a Vermont Democrat, said, “This horrendous event has got a lot of folks in Congress talking, but it doesn’t give us a license to ignore the lessons of George W. Bush in Iraq.”…

“I just don’t see it rising to a casus belli — or at least as a cause for a much larger military effort,” said Kenneth M. Pollack, a senior fellow at the Brookings Institution. “It is awful and it should remind us of who we are dealing with, and not have any illusions about that. But the political and military realities of Iraq and Syria remain unchanged.”

At the end of the long dark day, the the best plan is not to get involved in yet another Iraq quagmire. One American who bravely, but deliberately, endangered himself by covering the war in Syria, is not enough of a reason to slide back into this endless, disastrous war…

People argue you sometimes need to ally with a Stalin to beat a Hitler, but the myriad unnecessary wars, coups, and secret arming of groups over the past few decades makes that seem iffy. The Mujahideen freedom fighters trying to oust the Soviets from Afghanistan turned into al Qaeda. Saddam was a villain, unless he was fighting Iran. Manuel Noriega was a friend, and then he wasn’t…

Blowback is real. The CIA knew it and feared it in 1953, after they overthrew the Iranian government. 9/11 confirmed that U.S. actions can have deadly consequences for innocent U.S. citizens. As frightening as they are, terrorist groups — even ISIS — have motivations beyond their disturbed religion and their hoped-for theocracy.

Either cynically or sincerely, they have used, and they will use again, the interventionism of the United States to garner support for their horrible causes.

At a briefing Thursday, a reporter brought up anti-American comments from ISIL leaders: “I mean, even they are announcing, ISIL people in their message, whatever, the recorded message, other messages, that now we are in a war with America.”

“This is not about ISIL versus the United States,” State Department spokeswoman Marie Harf objected.