To this day Turkey has the largest standing army after the US of NATO members, it's not been a pushover for some decades now. Its also got a rather large number of armored units with few rivaling NATO members with the US as exception. It lacks Nuclear weapons (although it has the capacity to build and deliver, and participates in Nuclear sharing treaties, a bit like the Netherlands) and it's not better funded than say the UK, but it's pretty massive. Together with the reasons you mentioned (proximity) it makes a pretty decent case.