I have heard this fear expressed too that Trump would somehow bail on project Ukraine and NATO as a whole but I recall him also having similar bluster in 2016 and we know how that turned out. I haven’t seen any serious evidence to prove it and I personally cannot foresee a situation where he unilaterally just pulls out as a vanity project given what is at stake, and who the stakeholders are. If there was a case to be made I’d be open to hearing it tho, I am not an expert. I think it’s just dems slinging mud