Our Trigger Event

On December 1, 1934, a gunman killed Sergei Kyrov.  Kyrov was a Soviet revolutionary and was seen as something of a counterweight to the rising power of Joseph Stalin.  Stalin used the assassination of Kirov, an act that he is now suspected of ordering, as an excuse to clamp down on internal dissidents and those he considered a threat to his power.

Another example of this kind of behavior would be the Reichstag Fire in 1933. In both instances, an act of domestic terrorism, that was probably a false flag operation, set in motion a reign of terror.

I'm not talking about something like the 9/11 attacks here.  That was an attack against the country by a foreign invader.  These incidents were blamed on domestic opposition, and were used as a cudgel to get the population to support repression of dissent.  In both circumstances, if they were indeed carried out at the orders of the government, the operational security was air tight.  My guess is that the governments in question killed off the people who carried out the operation, then the people who killed them, then probably the next crew too.  Once you've liquidated people who are within a few layers removed from an operation, it's pretty easy to forget that the operation happened at all. 

So what could be the event in our country that can be used as a credible excuse to suspend civil rights and get rid of domestic opposition?  Could it be the assassination of a popular, but troublesome politician?  Or could it be the destruction of an important national landmark by those who are perceived to be opposing the country?  This wouldn't be a gradual erosion of citizens' rights and accumulation of power by the government.  This would be an almost overnight change from a moderately free republic to something much more restrictive and less representative of the will of the people.

So what do y'all see as a possible incident that would not only allow the government to suspend the Constitution, but would have the citizenry clamouring that they do so?