Let's be clear (and I'm again proving the point at the top of the thread) the US support for the Provisional IRA didn't cause peace to spontaneously break out in Northern Ireland. That was a bunch of pro democratic forces in both communities, aided by the official US involvement. All the funding of the IRA achieved was pointless, violent deaths.
On the contrary, without the actions of the IRA the UK would never have been willing to offer the kind of equitable terms that make a lasting peace possible. You can see the shift in their negotiating stance. I don't like it but you can't ignore the results.
Northern Ireland, although the US funding was always indirect/deniable.