The Obama administration is reportedly preparing a campaign to destroy the Islamic State militant group that could outlast the president's remaining time in office, according to a published report.

The New York Times, citing U.S. officials, reported late Sunday that the White House plan involves three phases that some Pentagon officials believe will require at least three years of sustained effort.

The first phase, airstrikes against Islamic State, also known as ISIS, is already under way in Iraq, where U.S. aircraft have launched 143 attacks since August 8. The second phase involves an intensified effort to train, advise, and equip the Iraqi Army, Kurdish Peshmerga fighters, and any Sunni tribesmen willing to fight their ISIS co-religionists. The Times reports that this second phase will begin sometime after Iraq forms a new government, which could happen this week.

The third, and most politically fraught phase of the campaign, according to The Times, would require airstrikes against ISIS inside Syria. Last month, the government of Bashar Assad in Damascus warned the Obama administration not to launch airstrikes against ISIS in Syria without its permission....