What is the objective of creating military alliances?

Countries form alliances to increase their effective power relative to another country or alliance.

The correct answer is Option 1 - Countries form alliances to increase their effective power relative to another country or alliance.

Traditional security policy has a third component called balance of power. When countries look around them, they see that some countries are bigger and stronger. This is a clue to who might be a threat in the future. For instance, a neighbouring country may not say it is preparing for attack. There may be no obvious reason for attack. But the fact that this country is very powerful is a sign formalised in written treaties and are based on a fairly clear identification of who constitutes the threat. Countries form alliances to increase their effective power relative to another country or alliance. Alliances are based on national interests and can change when national interests change. For example, the US backed the Islamic militants in Afghanistan against the Soviet Union in the 1980s, but later attacked them when Al Qaeda—a group of Islamic militants led by Osama bin Laden—launched terrorist strikes against America on 11 September 2001.