'We know China does not like these activities but, frankly, they are going to have to live with them'
Electronic surveillance of China's coast by US spy planes is continuing unaffected by the Hainan Island incident, according to intelligence sources.
Even at the height of the stand-off between Washington and Beijing over the 24 stranded aircrew, a US navy P-3 Orion anti-submarine plane is understood to have travelled down the coast of China on the edge of international air space.
The mission is expected to be followed within a week by another flight of an EP-3E Aries II - the same type of plane involved in the collision with the Chinese fighter jet southeast of the island.
Surveillance craft operating from the battle group surrounding the aircraft carrier USS Kitty Hawk have also been active as the ships moved through the South China Sea from Thailand over the past three days.
'At every stage, the US side has maintained that we intend to continue these flights as part of routine surveillance that we believe is important to national security and regional stability,' said one US official.
'That is why we could never fully apologise for our activities in international air space. We know China does not like these activities but, frankly, they are going to have to live with them. The US is acting fully within its international rights.'
The US operates about 200 flights each year involving a range of eavesdropping aircraft - part of a wider effort examining the growth of Chinese military assets along the coast.
Missile installations facing Taiwan and recently expanded ship and submarine patrols face particular scrutiny. Intelligence sources said the efforts may intensify as China's military grows.
A number of changes are expected as part of a comprehensive strategic review under way at the Pentagon, which will probably place greater priority on the future threat posed by China and other Asian countries. It is expected to confirm a decision to base a fleet of nuclear attack submarines in Guam. The vessels - designed originally to counter Soviet ballistic missile submarines - have been increasingly involved in undersea intelligence gathering operations in recent years. They can be used to deliver spies ashore or tap into undersea communications cables.
Beijing objected to coastal surveillance in private meetings with US officials before the collision and also tried to lodge protests through the Association of Southeast Asian Nations regional forum on security in 1998.
The issue surfaced in the negotiations over the release of the crew and will mark a key part of the agenda for talks next week, reportedly in San Francisco, to examine the incident and plot the return of the stranded EP-3E.
The US will seek to formalise acceptable interception techniques for Chinese fighters. It wants to build on a loose agreement between Beijing and Washington in 1998 acknowledging the need to create 'rules of the road'.
In the letter sent to Foreign Minister Tang Jiaxuan that marked an end to the crisis, Ambassador Joseph Prueher said the US acknowledged China's intention to raise the issue of reconnaissance missions.