"For sure the cooperation between the United States and Russia is a crucial one, I have no doubt," Tusk said at the G20 summit in Turkey, adding that a coordinated action against the Islamic State (ISIL) terror group should be their common aim.
Tusk stressed that "not only more coordination and cooperation, but also more goodwill" was important as he again blamed Russia for targeting what Brussels considers to be moderate opposition in Syria.
"Especially Russian actions on the ground in Syria must be focused more on ISIL, because in fact we cannot accept any actions against the moderate Syrian opposition," he claimed.
Russian jets commenced precision airstrikes against ISIL in Syria on September 30, following a request from Syrian President Bashar Assad.
Syrian Ambassador to Russia Riad Haddad confirmed in October that the strikes were carried out against armed terrorist organizations and not political opposition factions or civilians.