Recent discussions of the US possibly exploring some direct cooperation with Russia on the war against ISIS in Syria have come amid a shift by US officials on al-Qaeda’s Nusra Front, which they’d previously been pushing Russia to avoid targeting.

Secretary of State John Kerry is said to be one of the main administration officials in favor of the planned increased cooperation, and is heading to Moscow this week to discuss improved ties that would lay the groundwork for such an effort.

Acrimony toward Russia appears to be driving a lot of resistance to that effort, with reports that there is considerable opposition to the plan by both intelligence officials and some in the Pentagon arguing that the US and Russia have opposite goals in Syria and such a partnership can’t work.

That the intelligence community feels that way is unsurprising, as previous reports have suggested that most of them have been pushing to stop fighting ISIS in general and shift the war to imposing a regime change on the Assad government.

The Pentagon was said to be opposed to the CIA’s regime change stand, however, so their reluctance to work with the Russians likely reflects longstanding distrust, as well as the reality that keeping Russia at Cold War-level arm’s length has allowed them to push for major budget increases. It would be a lot harder for the Pentagon to argue war with Russia is imminent if they’re directly cooperating with them.