A member of the Syrian Democratic Forces stands guard near the village of Bir Fawaz, near Raqqa, during their offensive toward the Islamic State. (Delil Souleiman/Agence France-Presse via Getty Images)

Michael Flynn, the national security adviser to President Trump, shows visitors a map predicting what will happen to the Islamic State after its stronghold in Mosul is captured. It shows menacing black arrows reaching west toward future battlefronts in Iraq, Syria and beyond.

That’s the worry that motivates the Trump administration as it plans strategy against the terrorist group: Rather than a shattering defeat for the adversary, Mosul may be the start of a breakout to other regions. That may be one rationale for Trump’s controversial ban on travel from Iraq and six other Muslim-majority countries, which was rejected Thursday night by a federal appeals court. Defenders of the ban could argue that it might prevent a metastasis of the Islamic State into the West after its capitals are crushed.

“As Mosul falls, everyone [in the Islamic State] will move out,” said a senior Trump administration official. “ISIS will fall back into different areas. You could get suicide attacks again in Ramadi,” an Iraqi city that was liberated 14 months ago.

But many experts outside the administration see holes in Trump’s counterterrorism approach and worry that it could backfire. His rhetoric about “Islamic terrorism” has turned up the ideological heat, but it has frightened some potential Muslim allies at home and abroad. Trump has denounced the Obama administration’s strategy — which, however cautious, was slowly throttling the Islamic State — without having a clear alternative.

The travel ban has offended the Iraqi government, even as its elite forces bravely captured eastern Mosul. The casualty rate among the Iraqi Counterterrorism Service, which has done most of the heavy fighting, is about 30 percent, a high-level intelligence official said. Because that unit must rebuild its strength, victory in Mosul is at least six months away.

Then there’s the Iran conundrum. Flynn put Iran “on notice” after its Jan. 29 missile test, and the administration soon announced sanctions. But Tehran is also the United States’ de facto ally against the Islamic State in Iraq. Iran-backed Shiite militias haven’t turned their guns on U.S. forces, but they could — severely complicating the Islamic State campaign.

And there’s the puzzle of how to deal with the new alliance of Russia, Iran, Turkey and the regime of Syrian President Bashar al-Assad. Will the United States join them in a shared fight against the Islamic State? If so, would that mean abandoning the Syrian Kurdish militia known as the YPG, which has been the United States’ strongest partner against the Islamic State, but which Turkey rejects as a terrorist group?

During the presidential campaign, Trump urged an alliance with Russia against the Islamic State in Syria, and some officials have talked of driving a wedge between Moscow and Tehran. But analysts from the Institute for the Study of War caution that such a Russia-Iran split is probably wishful thinking.

Trump’s notion of partnership with President Vladimir Putin is also increasingly problematic. Congressional Republicans are wary about embracing Moscow. And last Friday, the senior administration official endorsed the hard-line statement by U.N. Ambassador Nikki Haley that Russia must withdraw from Crimea before sanctions are removed. The White House position on Russia is now “high standards, high expectations,” the official said.

The Trump team has criticized P resident Barack Obama’s plan for taking Raqqa as “poor staff work,” without having its own version ready. Some analysts worry that the Islamic State is regrouping as the new administration recalibrates policy. “Simultaneity and pressure are the keys going forward,” one U.S. commander said. He urged that the United States sustain its broad coalition, including the Syrian Kurds, to keep up momentum.

Victory in Raqqa could be a year off, the intelligence official warned. That would give the Islamic State many months to plan the global attacks that Flynn fears. Given this danger, some analysts speculate that Trump may eventually decide to clear Raqqa with thousands of U.S. troops from mobile units, such as the 82nd Airborne Division, which is already partly deployed in Iraq. That would be a decisive show of force, and it could get the United States in and out relatively quickly. But it would probably mean high U.S. casualties.

The bitter irony is that as Trump proclaims his anti-Islamic State campaign, al-Qaeda is becoming stronger in both Iraq and Syria, warn analysts from the Institute for the Study of War. This is a fight where easy slogans and rushed travel bans aren’t likely to provide a path to victory.

●A clarification about the National Security Council organizational chart described in a previous column: Susan Rice, former national security adviser, disputed a claim by Flynn, her successor, that she had 23 people reporting directly to her, compared with Flynn’s eight. Rice said she had just eight direct reports. Flynn’s spokesman said he had based his estimate on an organizational chart that Rice had given him.

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