I would argue that it was a function of global connectedness and relative freedom of movement.

Before the 1980s, it would have been very difficult for, for example, the IRA to coordinate with the Gadaffi regime in Libya, as there would be very few channels of communication that could be used. Conversely, today, it would be next to impossible to land a shipment of arms on even the remotest shores of Northern Ireland, since surveillance and monitoring technology has become so sophisticated.

The 1980s was the "sweet spot" between the rise of global communication and the rise of pervasive surveillance.