WARSAW - Excluding Russia from the Swift banking system would be a measure of last resort if the crisis in Ukraine escalates, the British and Polish foreign ministers said Friday.
"When it comes to sanctions, Swift is the nuclear weapon. It is the last resort and we are all aware of that," Polish Foreign Minister Grzegorz Schetyna said at a joint press conference in Warsaw with British counterpart Philip Hammond.
Russia last month said it would retaliate strongly if it were to be cut off from Swift, the global financial industry's secure messaging system to facilitate transactions.
"To be clear, this would be a very extreme sanction measure. It would have a very significant impact on the Russian economy," Hammond said, adding that discussion on the option was taking place "primarily in the US".
Western sanctions in 2012 cutting Iran off from the system for defying UN resolutions over its nuclear programme dealt a severe blow to the Islamic republic's economy.
Last year, the European Union and United States levied sanctions primarily targeting senior officials in Russian President Vladimir Putin's administration, amid fighting between pro-Russian separatists and Ukrainian government forces in the eastern regions of Ukraine bordering Russia.
EU foreign policy chief Federica Mogherini was upbeat on Friday about the sputtering so-called Minsk II ceasefire between the warring sides that the EU and Russia brokered last month.
"For sure the trend is a positive one, even if not perfect," she said in the Latvian capital Riga.
Both Ukrainian government forces and rebels claim to be withdrawing heavy weapons as called for in the truce.
But international monitors say they need greater access to their weapons inventories in order to verify the pullback.
Hammond on Friday urged the West to prepare "a whole range of potential sanctions options, so that we have maximum flexibility, maximum agility and maximum speed in reacting to any provocation, whether a breach of the Minsk implementation or whether it's a military offensive somewhere else in the Donbas region."