With a new national security adviser in place, U.S. President Donald Trump's administration can move on to other security matters. The first order of business will be to try to demonstrate that the United States is making real and rapid progress against the Islamic State in Syria and Iraq. But much of the administration's planning depends on Turkey, which has very specific ideas about how the offensive on the Islamic State capital of Raqqa should be carried out. The United States has room to make some tactical compromises with Turkey over how to conduct the operation. Still, since Ankara does not expect Washington to fully support its plan, it is looking to its allies in the Persian Gulf for help advancing its regional agenda....