WASHINGTON (AP) — President Barack Obama, in charting a new phase of American military engagement in Iraq, pledges that his war-weary country will not be “dragged back” into a lengthy conflict or become ensnarled in “mission creep.”

But recent U.S. military history is full of warning signs about the difficulty of keeping even a limited mission from expanding and extending. The prospect that this latest mission in Iraq could follow that pattern is particularly risky for Obama, given that he has staked so much of his legacy on having brought America’s long war there to a close.