Undated file photo shows China's J-20 stealth fighter jets taking part in their first-ever combat training over the ocean. China's J-20 stealth fighter jets have begun their first-ever combat training over the ocean, a spokesperson confirmed Wednesday. The J-20 is China's fourth-generation medium and long-range fighter aircraft and was commissioned into air force combat service earlier this year. (Xinhua)

BEIJING, May 9 (Xinhua) -- China's J-20 stealth fighter jets have begun their first-ever combat training over the ocean, a spokesperson confirmed Wednesday.

"It will help the air force better fulfill its sacred duty of safeguarding China's sovereignty, security and territorial integrity," said Shen Jinke, spokesman for the Chinese People's Liberation Army Air Force.

The J-20 is China's fourth-generation medium and long-range fighter aircraft and was commissioned into air force combat service earlier this year.

Shen said that since its commissioning the J-20 had taken part in air warfare training with J-16, J-10c and other fighter jets, boosting the air force's combat strength.

In recent years, the air force has been developing a series of new hi-tech military hardware under a strategy to emphasize both aerial and celestial warfare, attack and defense.