From CBS News:

China has taken a significant step in meeting Pakistan’s military needs with the completion of a militarily important naval frigate as part of an $800 million deal, which analysts say will further deepen Islamabad’s reliance on Beijing as a key supplier of military hardware.

Senior western diplomats based in Islamabad said China’s interest in expanding its military ties with Pakistan is linked to its overall ambition of emerging as a formidable military and defense power in the Asia-Pacific region, with the capability of eventually reaching out to influencing the oil rich Middle East.

China has supplied arms to Pakistan for more than 40 years. But this relationship which originally began as a largely military hardware supply tie-up has developed into a strategic partnership.