It seems too easy for it to be Ukraine.
Maybe someone else knew about what Maria did to her husband, perhaps General Doroshevich?
Maybe the peace talks were all a ruse to try and assassinate Dalton and Elizabeth?

Credit: Sarah Shatz/CBS
We finally learn how Pavel Ostrov died, and we probably should have guessed that Maria murdered him.
She looks like an evil murderous dictator.
Best line in the scene?
I am killing you, you worthless trash.
Jumping forward to present day, the episode picks up where it left off two weeks ago.
All of a sudden we see that Dmitri is back!
We havent seen him since the power went out over Moscow while he was fleeing on the train.
Looks like that plan failed, but at least we know hes alive after all that.
He breaks down and begs Henry to get him out of there.
Besides the dynamic between Bess and Henry, the relationship between Henry and Dmitri is probably my favorite.
This brings us to a wonderful video of Maria Ostrov as a former beauty queen.
This is the woman starting World War III?
Elizabeth gets permission to set up a summit in Geneva to plan peace talks and come up with negotiations.
Seems easy enough, except nothing ever goes according to plan, does it?
I would be perfectly happy if Maria Ostrov had him killed.
Also, I have a feeling it might become important to note Ukraine is very upset about the deal.
The negotiation includes the following compromises:
Maria Ostrov says she wants one more thing.
Dalton pretty much laughs in her face.
In order for the deal to go through, she needs to go back with something.
She asks for them to name the mole in her army and she will sign the deal.
They agree to keep the truth about Air Force One and Pavel Ostrov a secret.
This conversation leads us to probably the most heartbreaking scene of the entire season.
Cue the tears as Henrys face pretty much broke everyones hearts.
Bess confronts Henry, telling him that giving him up was for the greater good.
Henry is probably going to be feeling all kinds of things after he promised Dmitri safety.