It's never all one thing is it - this from the Irish Times records British Troops were initially welcomed by nationalists (not in any excusing later atrocities btw)
www.irishtimes.com/culture/day-the-troops-marched-in-to-nationalist-welcome-1.216524
The arrival of British troops was greeted with jubilation by Catholics, who viewed it as a sign that the RUC had been defeated, and the images of smiling nationalists 30 years ago still linger in the memory of many.
Tea, soup and sympathy were dispensed by Catholic women on a regular basis to the soldiers as they manned "peace lines" of barbed wire they had erected to separate the Protestant and Catholic areas. The Irish News said that while the introduction of British troops was "a drastic step . . . If the presence of troops means the withdrawal from Derry of the RUC riot squads and the hundreds of armed Orangemen . . . it may be the first step along the road to peace."
Getting back to the subject - there is a very interesting Netflix documentary about the killing of members of the Miami Showband - it's abundantly clear and shameful that the British government was complicit in that as in many other killings of innocent people. Of course that doesn't excuse any terrorists, but governments shouldn't ever be complicit in this way.