Keynes's argument of the International Clearing Union and the associated Bancor was primairly concerned with the need to manually balance trade balances rather than rely on FX exchanges. That would be achieved via manually setting FX exchange rates to heavily punish surplus countries (which should be happening normally in FX but isn't for various reasons).
The US chose to maintain a reserve USD pegged to gold instead back when they were running a massive trade surplus, but with the collapse of Bretton-Woods the situation in many ways has inverted. In any case, there is increasingly call by many in recent administrations, from Trump's policy advisors to Biden's Katherine Tao to return to the proposals of the ICU. While I don't think Trump's attempt to rebalance trade while still having the US reserve currency will work, I also don't think the Americans are that attached to that prestige to be willing to give it up in order resolve global trade balances and at home. It's not difficult to deal currency freezes with the right friends if you really wish, the real sting of US sanctions has always being barred access to the lucrative US market.
Of course, in the event that the ICU emerges, it would greatly harm the interests of surplus economies like China, Europe, Vietnam, Japan, etc, hence why they largely support the status quo of the US reserve currency rather than changing it, because they've decided that the benefits of surpluses exceeds the benefits of a deficit as a reserve currency.
The US chose to maintain a reserve USD pegged to gold instead back when they were running a massive trade surplus, but with the collapse of Bretton-Woods the situation in many ways has inverted. In any case, there is increasingly call by many in recent administrations, from Trump's policy advisors to Biden's Katherine Tao to return to the proposals of the ICU. While I don't think Trump's attempt to rebalance trade while still having the US reserve currency will work, I also don't think the Americans are that attached to that prestige to be willing to give it up in order resolve global trade balances and at home. It's not difficult to deal currency freezes with the right friends if you really wish, the real sting of US sanctions has always being barred access to the lucrative US market.
Of course, in the event that the ICU emerges, it would greatly harm the interests of surplus economies like China, Europe, Vietnam, Japan, etc, hence why they largely support the status quo of the US reserve currency rather than changing it, because they've decided that the benefits of surpluses exceeds the benefits of a deficit as a reserve currency.