On Monday, Secretary of State John Kerry described the broad outlines of a U.S.-Russia agreement for Syria. The plan includes three parts—(1) a cessation of hostilities, (2) improved humanitarian access, and (3) coordinated U.S. and Russian military strikes against ISIL and al Nusra. Buried deep in today’s New York Times story is a line that should affect how one evaluates the wisdom of working closely with Russia, especially with regard to the third element of the plan.

As the New York Times and a must-read story in Foreign Policy explains, many have grave concerns about downsides of military coordination with Russia. The set of concerns include the potential for: (1) providing Russia with insights into U.S. operational art in target selection; (2) creating a misimpression, especially among Sunni Muslims across the Mideast, of working alongside Putin in supporting Assad; and (3) bolstering Putin’s standing and ambitions.

So how does one assess those concerns and weigh them against the potential benefits? The New York Times story today is headlined, “Details of Syria Pact Widen Rift Between John Kerry and Pentagon.” But buried deeper in the story is a significant line which does not relate to the headline. It reads:

“In private, [Sec. Kerry] has conceded to aides and friends that he believes [the US-Russia deal] will not work.”

That sentence contrasts with Mr. Kerry’s words on Monday, in which he said:

“Now, I want to be clear as well that for all of the doubts that exist – and we know there are many – there will be challenges in the days to come. We expect that. I expect that and I think everybody does. But despite that, this plan has a chance to work.”

It is unclear why Mr. Kerry might privately think the deal will not work. If he believes the cessation of hostilities or humanitarian access will break down, then we should not actually reach the third element of the plan. According to his explanation of the agreement, a successful period of reduced violence and increased humanitarian access is a precondition for future military coordination with Russia. But, if Mr. Kerry privately believes that the plan will not work for other reasons, it raises the question: why then risk all the downsides of such an agreement?