He was speaking of these preparations as “eventual security against INVASION.”
Attained by preemptively invading all of South America? Hell, by that standard I'm surprised Hamilton didn't insist we simply conquer Europe itself and be done with it all, thereby preventing World Wars I & II over a hundred years later in the name of "eventual security."
He was speaking of co-operating with Miranda against Spain not a US invasion. Although Jefferson’s followers did invade Canada a few years later.