Russia’s overnight assault on Ukraine triggered a surge of calls Thursday for Western allies to completely cut Russia off from the global financial system, but fear of collateral damage is quashing the idea for now.

U.K. Prime Minister Boris Johnson, at a virtual meeting of leaders from the Group of Seven largest economies, advocated disconnecting Russia from Swift, the financial-messaging infrastructure that links the world’s banks. He joined a chorus of other senior officials, including Ukraine’s top officials, the foreign ministers of Estonia, Latvia and Lithuania, and senior U.S. lawmakers.