Even though Trump has said so many outrageous and horrible things, he still never fails to surprise me with his new levels of insanity and dangerous rhetoric every day. That said, does any NATO country actually not pay their dues to NATO? I highly doubt that story he told is true, especially since it's pretty obvious he's a pathological liar.
Most NATO Countries in 2017 did not pay their fair share of their NATO obligation; 2% of GNP, except four; Poland, Greece, Great Britain, USA. By 2021; end of Trump, there were ten countries who reached the 2% mark, due to Trump's negotiating and peer pressure tactics. There are now 30 plus members in NATO. Under Biden, who will let the tab slide, not all 30 are paying their share.
If Trump gets in, I expect more countries will pay their fair share. It is better than the US pulling out and Europe having to pay the whole tab, since 2% of the US's GNP of $22trillion, is a lot of cash, compared to 2% of Luxembourg's GNP.
This threat is all hyperbole. Say a land locked country, Switzerland, refuses to pay the full 2%, but all the countries around them pay, will Russia become the collection firm, who will then have to get permits, to air lift combat troops, over the paying countries, to get to the land locked country, without upsetting any of the paying countries? Only the Left will think so. This hyperbole makes member countries think, it may be better to pay up, than have to meet the collection goons, with their crooked mafia noses and baseball bats. Trump talks the way of the streets, and Trump can be quite funny, if you understand him in that context. I know the streets.
Back in 2016, Trump made a comment about having Putin find Hillary lost e-mails. This panicked the Left ,who were so panicked they seemed to react to a real threat to their quid pro quo scams and schemes. The cover spin became Trump and Putin were allies, even though Putin done much better under Obama and Biden; expanded territory. This above comment is the same thing and the Left appears to be doing one of its famous spin and wash cycles, to cover up something, subtly implied, but not stated by Trump.