They may be a bunch of rusty old T-55s, but Russia has almost twice the number of tanks as the USA. China has just a few hundred more than us.
Canada has almost 200, and they are right in our back yard.
Ya can't be too careful, if you know what I mean.
Possible wars to come? Syria has 4500 Soviet tanks.
How many of those will be in the hands of Isis?
Tank Strength by Country
and this one for cross reference
https://en.wikipedia.org/wiki/List_of_main_battle_tanks_by_country