"I think our expectation is that that will be a difficult fight for the Russians," CIA deputy director David Cohen said on Wednesday.Diego Herrera Carcedo/Anadolu via Getty ImagesDavid Cohen says the Russians are in for a "difficult fight" if they want to take back Kursk.Ukraine caught the Russians off guard when it launched a shock offensive into Kursk on August 6.Besides losing territory, Cohen said Putin now has to deal with Ukrainian forces within Russia.Reclaiming Kursk from the Ukrainians is going to be a "difficult fight" for the Russians, says CIA deputy director David Cohen.Cohen was speaking at the Intelligence and National Security Summit in Washington on Wednesday when he weighed in on Ukraine's shock offensive into the Kursk region.The surprise attack on August 6 caught the Russians off guard and allowed the Ukrainians to notch significant gains on the battlefield.The commander in chief of Ukraine's military, Oleksandr Syrskyi, said on August 12 that they'd seized nearly 400 square miles of Russian territory in just a few days.