Western nations agreed to unleash new sanctions aimed at further isolating Russia’s economy and financial system after initial penalties failed to persuade President Vladimir Putin to pull out of Ukraine.

A decision by Western nations to exclude some Russian banks from the SWIFT messaging system, used for trillions of dollars worth of transactions between banks around the world, was announced in a joint statement Saturday.

The move is aimed at Russian banks that have already been sanctioned by the international community, but can be expanded to other Russian banks if necessary, according to a spokesman for the German government.