“Icon” is episode five of season eight of Stargate SG-1.
Daniel awakes in a bed, injured, remembering something bad happening in the city, before the episode goes back three months. A tour group is being shown an ancient artefact in the grounds of a museum, a stargate, when it activates and a MALP comes through it. Then SG-1 (minus O’Neill, of course, so there are currently only three of them) comes through it.
The stargate is also a religious symbol, known as the Great Ring. So you just know that there is going to be a problem here.
There are two nations on the planet, which have been in a Cold War for years. The arrival of SG-1 causes fundamentalists to rise in one nations, resulting in civil war. And then the Cold War turns hot.
The events leading up to the present are told in flashbacks as Daniel is recuperating.