A(n) is when one country increases its army because others did.

An arms race is when one country increases its army because others did.

An arms race is a competition between two or more states to have the best armed forces. It is done by means of competitive acquisition of military material, military spending or the number of  people who serve in the army.

There is always a competitive nature to this buildup, hence the name race.

Some examples of an arms race are :

- The naval arms race between Germany and Britain from 1897 to 1914. It involved the costly building competition of Dreadnought - ships.

- The Cold War nuclear race between the United States and the Soviet Union. It led to large spending on nuclear missiles and the stockpiling of vast nuclear arsenals.