Ok fine, you can say that Karabakh belonged to Azerbaijan in 1918, but i can also say that Azerbaijan belonged to Iran in 1812, so if you claim that Karabakh is yours you should also claim that Azerbiajan belongs to Iran. My point being, 1918 was a long time ago, i think you should learn to let go.
By the way, if Azerbaijan tries invading Armenia, you can be sure that Iran will be more than willing to teach your Zionist loving President a lesson.