What produces String tension in Strings theory?

Question

In (classical) physics, tension describes the pulling force exerted by each end of a string, which is a one-dimensional continuous object, At the atomic level, tension is produced when atoms or molecules are pulled apart from each other and gain electromagnetic potential energy.

But there is no atomic level for strings of strings theory, so

What produces string tension in Strings theory?

Answer 1

Right now, when people talk of string theory, strings are the fundamental objects -- they aren't made up of anything. So they have an intrinsic property of energy, and energy per unit length corresponds to the string's tension.