ISLAMABAD (AP) — Pakistan on Thursday commissioned the first of eight Hangor-class submarine in China, a key step in its naval modernization as it expands its defense cooperation with Beijing, the military said.

The commissioning ceremony was held in the southern Chinese port city of Sanya, where Pakistani President Asif Ali Zardari was the chief guest. Pakistan’s navy chief Adm. Naveed Ashraf and senior military officials from both countries were also present. Zardari and other Pakistani officials have visited China many times in recent years.

Zardari, on an official visit to China, said that the induction of the advanced submarine was a “historic milestone” for the navy, reflecting Islamabad’s resolve to maintain a credible and balanced defense posture. He said Pakistan is capable of defending its sovereignty, protect maritime interests and secure key economic lifelines.

The Hangor-class submarine is widely believed to be based on China’s Type 039A design. It can carry a crew of 38, with additional capacity for special forces, and is equipped with torpedoes and anti-ship missiles. Pakistan in recent years has agreed to acquire eight of the submarines, with the final four to be built at Karachi Shipyard & Engineering Works in the southern port city.

Pakistan has long relied on its submarine fleet as part of its strategic deterrence against neighboring India, with whom it has fought three wars since gaining independence in 1947. During last year’s border conflict over Kashmir, Pakistan used Chinese-made J-10C fighter jets and claimed downing Indian warplanes, including French-made Rafale jets, which India has not confirmed.

Speaking at the ceremony, Ashraf said disruptions at critical maritime choke points are increasingly threatening global trade and energy security, underscoring the need for an advanced navy. He said the Hangor-class submarines, equipped with advanced sensors, weapons and air-independent propulsion systems, would help preserve stability in the region and secure vital sea lanes across the Arabian Sea and the wider Indian Ocean.

Ashraf said the name “Hangor” carries historical significance, referring to a Pakistani submarine that sank an Indian warship in 1971 — the first such sinking since World War II. He said the commissioning marked another chapter in the longstanding defense partnership between Pakistan and China.

Last year, Pakistan and China pledged to expand economic cooperation and investment under the China-Pakistan Economic Corridor, a flagship program of China’s global Belt and Road Initiative.