Counter-corruption advisor to Congress Paul Massaro says by some estimates, if the Ukrainians can hold out for 10 days, Vladimir Putin will be forced "by virtue of his lack of resources" to capitulate.
"The last I checked, the rouble's down 40 per cent - totally unprecedented - and we'll see what happens tomorrow when the market opens," Mr Massaro told Sky News host Andrew Bolt.
"He's got massive currency reserves, he does have quite a bit of money, but a lot of it is squeezed now - very heavily squeezed with the sanctions that have been put on."