Facts of the Case:
In 1971, India and Pakistan fought a war over the liberation of Bangladesh. (December) Pakistan lost the war.

The defeat of 1971 was especially humiliating for West Pakistan, especially considering the fact that the military dictatorship of General Yahya Khan, supported by senior officers including General Tika Khan, Meetha Khan, Kulli Khan, and Rao Farman Ali. They were completely confident that the West Pakistanis would be able to crush the Indian Army who was also supporting the Bengali resistance fighters known as the Mukti Bahini. Under leadership of Sheikh Muzibur Rehman (Banga - Bandhu) - Awami League party
The problem was that the West Pakistani couldn't accept the defeat as they had been made to believe that they were invincible.

Indian Army Chief - Sam Manekshaw
However, after the creation of Bangladesh, the Pakistani people revolted against the military dictatorship.

Zulfiqar Ali Bhutto became the Prime Minister of Pakistan.

In 1972, the Pakistani government had to sign the Shimla Agreement (2 July 1972, Indira Gandhi + Bhutto) with Inai which the Pakistani regarded as humiliating. (Peace Treaty - seeking to reverse of consequences of 1971 war)

3 Dec. 1971 - Indira Gandhi attack
17 Dec. 1971 - West Pakistan Surrender
Jan. 1972 - Bangladesh create after war

The same year, Zulfiqar Ali Bhutto, who was himself a mujahir [muslims originally from India (Bhutto was from a businessman family from Karnal, Haryana], gave a famous speech in Karachi, and the opening words were, "we shall eat grass, we shall eat nothing. But we will make a bomb against India."

Therefore, the very next day, the Pakistani Leadership initiated a top-secret military project called Project 706, which was to develop Pakistan's first nuclear weapon.

The main aim of Project 706 was to develop a nuclear weapons program by the Pakistani establishment, which would counter India's influence in South Asia. [which is apparently a legally incorrect step taken by Pakistan. Countries might have a lot of weapons to use, but they always say that it is for "peaceful purposes". The UN bans the countries from starting a war on one another under Article 2(4) of the UN Charter.]

However, the biggest problem for the Pakistani administration was that they had no nuclear power plants or research regarding the same.

[When Zulfiqar Ali Bhutto threatened to destroy India, the scientists pointed out that the country needed to have the technology and resources to actually make the threat work.]
At this critical phase, a Pakistani scientist and nuclear physicist Dr. Abdul Qadir Khan, stepped up to develop the Pakistani Nuclear Weapons Program (PNWP).

However, the PNWP was illegal from the very beginning as it had developed out of stolen foreign technology and operated without international supervision.

[The crime is nuclear espionage and is punishable under waging a war against a state and sedition. Pakistan defended AQ Khan when he was to be prosecuted under Dutch laws. Pakistan believed that it was perfectly okay for their country to develop a nuclear program out of stolen foreign technology. This might sound morally correct but it isn't legally correct. AQ Khan was seen as a thief and a smuggler who stole foreign tech and ran back to his country to develop the PNWP]

The PNWP was developed in 1988 and Dr. AQ Khan termed it as the "Islamic bomb"
Pakistan then held a host of other nations, including Iran, Libya, and North Korea, to develop a clandestine nuclear weapons program in total contradiction of established norms of international law.

[It was this Islamic bomb, AQ Khan would have sold the tech for free, but he was a businessman and took proper money from dangerous regimes. Pakistan knew of the work done by AQ khan as Pakistan actively supported its scientist but denied it all when it came to taking responsibility.]

A.Q. Khan - Father of Nuclear Bomb of Pakistan
Nuclear Espionage - It is the purposeful giving of state secrets regarding nuclear weapons to other states without authorization.

Article 2(4) UN Charter
All members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the purposes of the United Nations. It is the heart & sole of the UN Charter. It is also led down by ICJ in Aerial Atlantique Case (1999)