I was forced to do this in my current game. Russia asked me to DoW Brazil (who I'd ravaged down to 2 cities alongside Russia back in the early Renaissance and I was now in early Industrial) but I was currently fighting the Aztecs (I'd nearly destroyed them earlier and their peace treaty gifted me all but one of their cities) at the behest of Poland, my ally since the beginning of the game.
I asked for 10 turns while I finished dealing with Aztecs, but as I was moving reinforcements down to Tenochtitlan (my city since an earlier war but I'd moved all the units out of it to attack Aztecs last city) I noticed a large amount of Brazil's units moving through the no-man's land between us towards the unguarded Aztec capital... I checked diplo status and he listed as Guarded with the newest modifier being my warmongering was a global threat, so I took a pre-emptive strike and DoWed him immediately so my cavalry division (four cavalry) could decimate his archers and siege this turn.
My one Samurai who'd discovered his army had ended up surrounded by his units before I DoWed (a pair of longswordsmen a pair of pikes an archer and two catapults - he had a few knights but not close to samurai and a river separated us). I quickly dispatched a catapult and did a number on the archers. On his turn he left my samurai with 12 health (didn't have march yet, fresh unit) but my cavalry managed to dispatch the remaining ranged units so I could embark him into the nearby inland ocean (pretty large one about 8 hexes wide and 20 hexes long but no connections outside of continent) until my cavalry and Ashigaru division (two musketmen) holding a nearby mountain pass helped the cavalry dispatch the remaining forces.
By this time I'd started razing the Aztecs final city so my main army divisions were returning (except a few landsknecht that were healing up from taking the brunt of the city's punishment) so I managed to regroup and sack one of Brazil's last two cities. He sued for peace while I was beating his final city to a sliver so I accepted and pulled my armies back to rest up and garrision my nearby cities (except for the Ashigaru which I kept nearby because of my 10 turn promise to Russia). About 3 turns later Catherine popped up and I accepted and re-DoWed Brazil. I used my two musketmen in support of her army of swordsmen and knights and helped her take his last city (since I'd already eliminated one civ with a Major penalty and taken one of Brazil's last two with another Major). None of the other civs (all good friends with me) reacted until late Industrial... both Poland and Austria let our DoFs expire and now show Guarded with the modifier that my warmongering is a global threat, but have taken no actions other than that (Poland even keeps renewing our Open Borders, primarily because terminating it would leave a handful of cities completely isolated since he crammed a few into holes in my empire).
I've just entered Modern and still no denouncement or any severe fallout from my actions. Korea and Russia remain my loyal allies (although Korea is also close to Poland so it'll be interesting to see with whom they side) probably because Korea was part of the war against the Aztecs and Russia part of the war against Brazil.
I really hope Poland rises against me in the near future as he and I are the dominate empires... his is expansive, controlling about half of our original continent (I might have a third with the remaining divvied between Austria and Korea) with about double my cities and both of us are spread worldwide, I have more cities on the "new world" - including the two capitals of the now extinct Aztecs and Brazil - but he gobbled up all the isolated island chains between our continents. He's only one or two techs behind me so I'm looking forward to some fun fights when we both get Flight, but we've had so many positive modifiers (including both being Autocracy - the only two with an ideology) and have been close friends for so long, I don't wish to be the one to strike the first blow...
It can even happen on the same turn you signed a peace treaty. 
(if AI civ A plays after your turn)
