Russian President Vladimir Putin and Ukrainian President Viktor Yanukovych have held talks in the Black Sea resort city of Yalta.
It was Putin's first visit to Ukraine since he returned to the presidency in May.
The presidents discussed Ukrainian purchases of Russian natural gas, but no agreement was reached.
Kyiv has been seeking a renegotiation of a 2009 agreement that it claims set exorbitant prices. Moscow says any discount would depend on Ukraine allowing Russian state gas giant Gazprom to take over the country's gas-transport system or join a Russian-led customs union uniting Belarus, Kazakhstan, and Russia.
The two leaders agreed on an additional summit in Russia later this year and another visit by Putin to Ukraine in 2013.
Based on reporting by Interfax, ITAR-TASS, and Reuters