That hasn't been true for many years.

Excluding the US, all the other countries put together would be around 2 million active personnel. Of which Turkey is the largest at 300k.

Due to language issues, cultural issues, and political issues they're hardly likely to pull together, and especially now, with Trump and Vance openly insulting their NATO partners.

The only leverage NATO would be able to provide the US today would be political.

And don't forget that Russia via the Ukraine SMO has been systematically demilitarising the entirety of NATO over the last 4 years. The evidence for this is in the panicked pronouncements of the NATO vassal states like Germany. More recently Poland has refused to send their patriot systems to the Iran conflict.