MOSCOW (AP) — The leaders of Russia and Serbia have pledged to expand their energy and military ties.

Russian President Vladimir Putin said Wednesday after hosting his Serbian counterpart Aleksandar Vucic that they discussed Russian natural gas supplies to Serbia.

Putin said Russia is willing to continue pumping its gas to Europe via Ukraine but added that Ukraine so far has offered unacceptable conditions for transit. He voiced hope that Russia and Ukraine could reach a compromise.

Vucic said the two countries also have “excellent” military cooperation. He said Serbia is awaiting the delivery of more Russian weapons.

The Serbian leader remarked that NATO’s 1999 bombing campaign against Serbia wouldn’t have been possible if Putin had been in charge of Russia then.