[jamwil]

I was talking about this with someone the other day… How many real terrorism threats have been preceded by the terrorist telegraphing their intentions with a phone call beforehand? My prior is that this number is essentially 0 and we should ignore bomb threats as a society.

[echoangle]

Here's one: https://en.wikipedia.org/wiki/Omagh_bombing

Two: https://www.justice.gov/archive/usao/nye/pr/2012/2012nov08.h...

Three (not sure if the caller was the one planting the bomb here): https://www.theguardian.com/uk-news/2015/may/01/bomb-aimed-a...

Probably not super common but it does happen from time to time. And imagine ignoring a bomb threat and then it's real, you probably would not want to be responsible for that.

[hoppyhoppy2]

The Weather Underground often warned the targets of their bombings via phone call. (I guess their goal was to attack gov't institutions and make a political statement, not to kill lots of people.) This was in the late '60s-'70s.

[robrain]

The IRA (Irish terrorists, for Americans confused at the acronym, or maybe confused at what the IRA did) did occasionally phone warnings and occasionally the information was accurate. Code words were used to authenticate the threat.

[roryirvine]

The PIRA actually do seem to have intended to give accurate warnings when they planted bombs, in Belfast at least. There were inevitably cases when the information was garbled or misunderstood but the use of codewords & the practice of delivering the warnings to a known set of media outlets was at least an attempt to minimise these.

The downside was that the vast majority of warnings were hoaxes - bomb scares were dozens of times more common than actual bombs.

The other main groups - INLA, UVF, and UFF/UDA also got in on the hoax game, but didn't often do real bombs (and didn't always give proper warnings when they did - see the UVF's Dublin & Monaghan bombings for a particularly grim example).

But real bombs were just common enough that the hoaxes from whatever source had to be taken seriously and so they caused huge amounts of disruption, probably more than anything that actually exploded.

[SteveNuts]

Logically that probably makes sense, but it would require everyone in the chain of command agreeing to that policy, and there’s no way that would ever happen from a liability standpoint.

[umanwizard]

It was standard practice during the Troubles in Northern Ireland, for example.

[rndmio]

The IRA bombs in civilian areas in the uk almost always had phone calls that preceded the bombs going off.