China and Pakistan are comrades in arms thanks to India and the US.
Pakistan formally recognised the Peoples Republic of China on 4 January 1950, and it was not guns and missiles that made it reach out. Pakistan was seeking a market for its jute and raw cotton, while looking to buy coal; in China, it found a willing trade partner. At the National Press Club in Washington DC on 4 May 1950, Prime Minister Liaquat Ali Khan said that Pakistan had recognised China, "accepting an established fact and in order to ease [its] flow of trade".
Things assumed the shape of military ties more than a decade later, when after its 1962 war with India, China began strategically capitalising on the India-Pakistan rivalry. The amicable border settlement between China and Pakistan in 1963 further facilitated the new turn of events.
However, China-Pakistan defence ties, which now account for one-third of Pakistan´s arms imports, began in right earnest only after the 1965 war, when the United States embargoed all military aid to Pakistan and even blocked supplies that were in the pipeline.