There’s also the fact that that money isn’t strictly money “wasted” - you can effectively double dip by using the funds to buy domestic or allied materials, essentially just circulating the money around your economy and creating defense-related jobs. Not that you wanna go full MIC but it’s not like Europe is gonna be flushing 800B down the drain.

Keep in mind he’s also making sure to publicly put the ball in Trump’s court regarding maintaining the relationship - especially obvious with his remark about “well of course they wouldn’t want to side with Russia”. Expressing optimism and openness publicly while maybe have reservations privately strikes me as a shrewd political stance.