The European Union called on Russia on Wednesday to avoid worsening the crisis in Ukraine or face further sanctions.
The EU also said it wants to continue negotiations on a free-trade deal with Japan, which officials see as crucial for economic growth.
"We call on Russia to refrain from any steps to further destabilise Ukraine, instead to engage in a diplomatic resolution of the crisis," European Council President Herman Van Rompuy told a news conference with Japanese Prime Minister Shinzo Abe following a summit in Brussels.
"Further steps in destabilising Ukraine will call for additional sanctions," Van Rompuy said.
(Reporting by Robin Emmott; editing by Adrian Croft)