Former CIA Director David Petraeus is backing President Donald Trump’s argument for strategic cooperation with Russia, saying he can imagine times when the US could overlook its conflicts with Russian President Vladimir Putin.

“It’s very clear what Vladimir Putin’s objectives are. In many cases, they are unacceptable to us and NATO and our allies and partners around the world,” Petraeus told CNN’s Frederik Pleitgen on the sidelines of a German Marshall Fund event in Berlin celebrating the 70th anniversary of the Marshall Plan. “Having said that, there could be some convergence of interest when it comes to the defeat of the Islamic State and al Qaeda, and perhaps stopping the bloodshed in Syria as an overall objective as well.”

Trump has said positive things about Putin and Russia in general, adopting positions that are out of the GOP mainstream when it comes to the US adversary.

But Petraeus cautioned: “I again would go into this with my eyes very wide open and a very, very realistic appraisal of what Russia has done and what Putin would like to do.”

He concluded: “I think strategic dialogue with one’s adversary is not something that should be avoided. I think you should actually pursue it.”

Petraeus also said he expected more troops to be sent to the Middle East to fight ISIS, pointing to Afghanistan in particular. He declined to weigh in on the administration’s recent decision to conduct a ground raid in Yemen, saying he was not aware of the intelligence that emerged from it.

But he did reiterate that he thought it would be a mistake for the US to roll back its commitment to foreign aid.

“There’s a saying that diplomacy without the threat of military force is like baseball without a bat. It goes the other way as well,” he said. “You’ve gotta have the diplomatic elements, and often times you don’t need to actually swing the bat if you have successful diplomacy.”