10.Rebus sic stantibus should not be confused with force majeure. Force majeure excuses the obligor to perform only if there is an irresistible (and unforeseeable) obstacle. In force majeure, the performance must be physically or legally impossible and must not be merely more onerous to perform. Thus, in a nutshell, the fundamental difference is that, unlike rebus sic stantibus, force majeure does not include economic hardship nor even economic impossibility.