The security dilemma might force states to form new alliances or to strengthen existing alliances. "If offense has less advantage, stability and cooperation are likely". According to Glenn H. Snyder, under a security dilemma there are two reasons that alliances will form. First, a state that is dissatisfied with the amount of security it has forms alliances in order to bolster its security. Second, a state is in doubt about the reliability of existing allies in coming to its aid, and thus decides to court another ally or allies. According to Thomas Christensen and Jack Snyder, in a multipolar world two types of alliance dilemma exist which are contrary in nature. These alliance dilemmas are known as chain ganging and buck passing.