Boris Johnson is pushing for governments to block Russian banks from using Swift, an international messaging system that is vital for transferring money.
The prime minister reiterated on Friday that the measure was an important way strike back against Vladimir Putin as Russian tanks approached Kyiv.
What is Swift?
Swift stands for the Society for Worldwide Interbank Financial Telecommunication. Set up in 1973, it is a crucial part of the plumbing that facilitates flows of money around the world.
It is a secure messaging system that allows around 11,000 financial institutions to talk to each other and authorise payments. When a payment is sent from one bank to another, they receive a message via Swift before going ahead with the transaction. Around 40 million transactions are carried out using Swift each day.
It is operated as a co-operative by 2,000 member banks and is based in Belgium. Central banks including the Bank of England oversee the running of the co-operative.
Swift is a neutral organisation that cannot issue its own sanctions. A decision to block Russian banks from using the system would need to be agreed upon by governments.
Would a ban from Swift hurt Russia?
Boris Johnson has put forward the case that excluding Russia from Swift would make life difficult for Mr Putin by preventing Russia from sending and receiving payments.
Speaking on BBC Radio 4’s Today programme, Defence Secretary Ben Wallace Wallace explained: “When you pay Russia for its gas, it probably goes…