John Kerry, Pentagon at odds over pact with Russia over Syria

On Tuesday at the Pentagon, officials would not even agree that if a cessation of violence in Syria held for seven days — the initial part of the deal — the Defense Department would put in place its part of the agreement on the eighth day: an extraordinary collaboration between the United States and Russia that calls for the American military to share information with Moscow on Islamic State targets in Syria.

“I’m not saying yes or no,” Lt. Gen. Jeffrey L. Harrigian, commander of the United States Air Forces Central Command, told reporters on a video conference call. “It would be premature to say that we’re going to jump right into it.”

White House officials were also dubious. “I think we’d have some reasons to be skeptical that the Russians are able or are willing to implement the arrangement consistent with the way it’s been described,” Josh Earnest, the White House press secretary, said Monday at a briefing. He added, darkly, “But we’ll see.”

In Mr. Kerry’s view, the administration has needed to do everything it can to restrain the forces of President Bashar al-Assad of Syria from continuing to bomb civilians. Once the Russians entered the war, that meant making the deal with President Vladimir V. Putin — one in which the Russians would pressure Mr. Assad to stay out of the skies.