French soldiers prepare to deploy at the Satory military base, near Paris. [Photo/Agencies]

As China's comprehensive capability and international interaction grow, discussions have emerged on how to protect its overseas interests.

Domestic strategists tend to believe that by establishing military bases in another country's territory, one nation must form alliances with the host country, and make security promises to the latter. Thus they oppose the idea of obtaining overseas military bases, claiming it is incompatible with China's decades-old non-alignment policy.

To make clear the relationship between overseas military bases and alliances, it is necessary to track their historical evolution first. There are many reasons why a state sets up military bases outside its own territory: to maintain overseas trade, to ensure access to strategic materials, to support an ally or weaken an enemy, sometimes even to show its determination to defend global interests.

In many instances, establishing overseas military bases is linked with military alliances. The most typical cases must be the United States and the Soviet Union during the Cold War, both of which used military bases to shape their sphere of influence, control alliances, and honor their promises to defend allies.

Even after the collapse of the Soviet Union, the US still stations troops all over the globe, and uses them as ties to connect it with its worldwide allies. And for most of US' allies, these bases are important signals of their alliance.

Sometimes moves of troops in an ally's territory might even show changes in alliance relations. During the 2003 Iraq War, Saudi Arabia forbade US fighter planes to take off from its territory.

With world security conditions becoming complicated, the US has its considerations, too, such as worries of being involved in an ally's conflict with its enemy. Besides, conflicts between US troops and local people are also on the rise; which is increasing the cost of maintaining permanent troops in overseas military bases.