(NBC NEWS) -- The world powers known as the Group of 7 are backing out of a planned summit in Russia and will meet on their own instead - a diplomatic move intended to punish Russia for annexing part of Ukraine.
The G7 countries - the United States, Britain, Canada, France, Germany, Italy and Japan - were supposed to meet in Sochi in June for the summit, known as the G8. But they said Monday that they would suspend that plan "until Russia changes course."
The seven countries said in a joint declaration that they will meet in Brussels in June. They condemned Russia's "illegal attempt" to annex Crimea, the Ukrainian peninsula where Russian forces took control earlier this month.
"This clear violation of international law is a serious challenge to the rule of law around the world and should be a concern for all nations," the declaration said.
The West has already imposed some sanctions on Russian officials. The seven countries said they would intensify those sanctions, and hit sections of the Russian economy, if Russia escalates the conflict.
Russian troops have massed on the border of eastern Ukraine, raising fears that Russia will mount an invasion of the Ukrainian mainland. Russia has said it has no plans to do so.