Read the given passage carefully and answer the questions that follow

The binding force of international law is based on the supreme fundamental norm or principle known as Pacta sunt servanda. This means that agreements entered into by States will be respected and followed by them in good faith. This is a well established and recognised custom of international law. The customary principle of international law has now been codified and finds mention in Article 26 of the Vienna Convention on the Law of Treaties, 1969

The principle of Pacta sunt servanda is also based on the actual practice of the States. It emphasises the importance of the agreement entered into by States and regards them as the basis of international law.

There is a view that to assert the binding force of international law is based only on the principle of Pacta sunt servanda is far from the truth. It fails to explain the binding force of customary rules of international law which are not based on agreement between States. The realisation that international customary law does not rest on agreements and that the tenet, Pacta sunt servanda is itself a rule of customary law, led to new formulations of the basic norm.

Kelsen has decided on a formula which takes into account usage, as the fact which is the origin of the rules of international law - 'States ought to behave as they have customarily behaved".