What allies? The ones who Trump got on their asses to up their spending on their own defense? The fact is that we cannot afford some of these so called allies. We are broke and when they refuse to simply get out our way (use our equipment/soldiers flying over their country) then they don't have value that even comes close to breaking even on the treasure we pissed away. Cost vs value is not there.USA spent a long time building up and investing in an alliance system .. only to have one President claim he does not want it anymore
USA will be in massive trouble if we have no allies.
USA will be unable to project power.
Some NATO members are spending a very significant amount on their military
( Poland, Baltics, Finland .. basically everyone which had been under or attacked by Russia in the past )
France never trusted the USA nuclear backing .. so they got their own Nukes, as well as building their own fighters