Robert Gates, US defence secretary, said Washington will respond to Beijing’s development of a new stealth aircraft and long-range anti-ship missiles, sounding a warning note at the start of a long-awaited trip to China.

Speaking before he arrived in Beijing on Sunday night for a visit intended to bolster relations, Mr Gates acknowledged that US intelligence had failed fully to anticipate China’s development of the J-20 aircraft, photographs of which appeared on the internet last week.

Noting that he had been concerned about China’s development of anti-ship missiles “ever since I took this job”, he added, referring to both technologies: “They clearly have potential to put some of our capabilities at risk and we have to pay attention to them; we have to respond appropriately with our own programmes.”