Losing territory after losing a war, especially one that you start, is simply a fact of life. Even excluding the results of WWII, which had things like Russia keeping bits of Poland they took due to agreements with the Nazis, the Baltic states, and parts of Finland, there have border changes large and small from conflicts. Other than the border changes around Israel, some of which (Sinai, Gaza) have been returned and others are not officially annexed (much of West Bank) you don't hear a lot of international angst. Pakistan lost the war with India, and East Pakistan (now Bangladesh) was created as the result of Indian arms - no UN resolutions about that. China/Tibet, a cause you rarely hear about. I could go on and on.
Part of the problem with "getting territory back through a political process" is if one side is unwilling to recognize the other as a legal entity, side #2 is unliely to be willing to give land back especially when said land has been used for attacks in peacetime.
Part of the problem with "getting territory back through a political process" is if one side is unwilling to recognize the other as a legal entity, side #2 is unliely to be willing to give land back especially when said land has been used for attacks in peacetime.