Explanation:

Being a sovereign state, India can acquire foreign territories or cede own territories according to the modes recognized by international law, i.e., cession (following treaty, purchase, gift, lease or plebiscite), occupation (hitherto unoccupied by a recognized ruler), conquest or subjugation

• Article 2 -  It relates to the admission or establishment of new states that are not part of the Union of India.
• Article 3 - It relates to the formation of or changes in the existing states of the Union of India. In other words, it deals with the internal re-adjustment inter se of the territories of the constituent states of the Union of India.
• The Supreme Court held that the power of Parliament to diminish the area of a state (under Article 3) does not cover the cession of Indian territory to a foreign country. Hence, Indian territory can be ceded to a foreign state only by amending the Constitution under Article 368.
• The 100th Constitutional Amendment Act (2015) was enacted to give effect to the acquiring of certain territories by India and transfer of certain other territories to Bangladesh in pursuance of the agreement and its protocol entered into between the Governments of India and Bangladesh. Under this deal, India transferred III enclaves to Bangladesh, while Bangladesh transferred 51 enclaves to India.
• The settlement of a boundary dispute between India and another country does not require a constitutional amendment. It can be done by executive action as it does not involve cession of Indian territory to a foreign country. It was ruled by the Supreme Court in 1969.