I believe that they will be a bit puffed up and agree on peace. It is not advantageous for them to destroy the economies of their countries by war and become beggars.
Exactly, nobody wants the war because during the peace time, the trade is going very well, there are many agreements between governments, that apply to different branches of industry, for example financial or energy industry.
Also, the war in modern times between two highly developed countries look totally different, there are not many soldiers going forward to the land of the enemy, there are thousands of aircrafts, drones, sattelites and different military technology, which usually might be used for killing people.
The another problem we encounter in such a case, is that many countries have access to nuclear weapon, which is very important factor when anyone is thinking about attacking the independent place.