TLDR: How would you start a war between allied nations?
A little bit of background. My story takes place in world where people have the ability to use life force much like electricity. Three main races, each with a kingdom in roughly the same area. Historically, the third race waged war on the other two until they found a way to fight back. Centuries later, the two kingdoms are still at peace while the third is mildly ostracized. Every so often there are storms that can recharge the second race.
Now, my main character's goal is to start a war between the two allied nations without them realizing that they're being manipulated. I'm looking for thoughts on how to start the war.
Initially I'm thinking I'd start with cutting communication between them. As you fake war preparation with one side, the other responds with real preparation. Do this until it escalates and you don't have to fake things.
Another idea I have is creating a competition for the resource of the storm. Right now it's important to one race but not the other and I can't think of a reason why they would fight over it when only one of them needs it.
Any insight? Assassinations? Kidnappings? How to fake it to make it look like the royalty of each side is personally committing these acts?
Thanks in advance.