Future of just war

There are only two legitimately justified grounds for going to war as far as I know currently in international law. 1. Defense from an unjust invasion or attack. 2. Humanitarian intervention (for stopping crimes such as genocide and other crimes against humanity). Both motives require high standards of proof because of the moral seriousness of war. But in the future I wouldn't be surprised if other reasons for just war are added. This is because of the nature of globalization in bringing the world "closer".

Consider pollution. I can imagine that nations in the future may go to war with each other because one nation's pollution affects a neighboring country so much that many deaths occur in the later country from such pollution. Pollution is one of those modern phenomenon that crosses national boundaries and ought not be regulated internally according to state's sovereign rights because its effects are global. 

However, if pollution affects others and those people have exhausted all diplomatic and other methods to try and stop the offending nation from harming their people through pollution, may they go to war to stop or curb it?

The issue then will be formulating just war principles in going to war in such cases such as the one here about pollution. How culpable must a country be in allowing pollution to affect people in another country for a neighboring country (or any other country seriously affected) to justly go to war to force the polluting country to comply in changes to domestic policy so that the harmful pollution is stopped or reduced? Ought economic considerations also be allowed as justification? If the pollution affects another nation's economic development by spoiling their resources but has few or not very serious health effects for the people (say because few people live near polluted areas), can that nation still justifiably go to war to stop or reduce the pollution using deadly force? 

What will the principles of just war theory be? There seems to be so much gray area that such principles will be difficult to formulate. Philosophers need disparately to apply their skills in this area in the future. Matters of such importance and difficulty ought not be left to lawyers.