The second major constraint on the F-22's ability to influence the balance of power in the Pacific relative to the J-20 is the Raptor's limited room for improvement compared to its Chinese counterpart - or even its lighter counterpart the F-35. The F-22 entered service using specialised but somewhat obtuse software, computer architecture dating back to the early 1990s and a poor core processor speed of just 25MHz. The fighter is as a result extremely difficult to upgrade - with even basic adjustments such as equipping it with more modern munitions including AIM-120D and AIM-9X air to air missiles taking several years to implement. Use of these dated systems were a result of the length of fighter’s development program, which took 24 years in total and well over a decade just to go from design to production. The fighter's avionics were considered dated long before it entered operational service in December 2005. While the U.S. operates a number of dated fighters, many older than the F-22, there are two key reasons why the age of the Raptor's systems could prove an insurmountable obstacle.
Unlike the F-15, which remains in production to this day, the termination of F-22 production has made it extremely difficult to upgrade and prevented the Air Force from modernising the design as was done with its fourth generation predecessor. While the Raptor's could potentially be improved at great time and expense, regular upgrades needed to keep the fighter at the cutting edge against near peer platforms remain an unlikely prospect. The fighter’s stealth profile and airframe, while formidable, are increasingly surpassed by next generation systems which have been developed since the Raptor's design was finalised. While these could be modified and updated on future variants should production lines still be running, their closure has eliminated such a possibility. As it stands, the Air Force has little room to improve the quality of its F-22 Raptor fleet. The J-20 by contrast, only at the beginning of its production run, has seen its capabilities revolutionised within a year and these continue to be modernised apace - from new ramjet powered air to air missiles to more sophisticated stealth systems and cutting edge new engines. The J-20 is thus set to remain a world leading and highly relevant fighter long after the Raptor has passed its usefulness - very likely integrating sixth generation technologies as the F-35 and Russian Su-57 are also set to do.
The third major constraint on the Raptor's ability to influence a war in the Pacific is that the fighter's design was heavily influenced by the need to prepare for a potential for a war against Warsaw Pact forces in Europe. The fighter was commissioned and conceptualised in the 1980s with the primary goal of defeating the Soviet fourth generation Su-27 over European battlefields, a role for which the F-15 fell short. The capabilities of the F-22, particularly its range, strongly reflect the needs of the Cold War European theatre more than any other - and the Raptor is until today better suited than any other NATO fighter to a potential war with Russia in Europe. In the Pacific theatre however the United States had never anticipated a near peer threat, with China in the 1980s relying primarily on the Vietnam War era J-7 for aerial warfare against which the F-15 and even the F-4E Phantom were more than adequate to ensure an advantage. While the Raptor has been pressed into service in the Pacific it was never designed for such a theatre - as reflected by its wholly inadequate range and resulting high reliance on aerial refuelling to reach its targets. As noted in a study by the RAND corporation think tank, this reliance on aerial refuelling has made Raptor highly vulnerable to becoming stranded should its non stealthy, bulky and highly vulnerable tankers be destroyed - a likely outcome should they attempt to ferry F-22s anywhere near Chinese territory. This lack of range and reliance on highly vulnerable and tankers which lack radar evading capabilities compromises the potential combat performance of the F-22 in Asia significantly. Indeed according to the study by RAND Cooperation, even if assuming highly unrealistic optimal conditions under which the F-22 were deployed and managed to score a perfect number of kills against Chinese fighters and no combat losses - the fleet would still ultimately be destroyed as remaining Chinese fighters would be able to target tankers and prevent the F-22s from returning to their bases once the American fighters had expended their ammunition. This would force the F-22s either to crash into the sea or land at Chinese bases. The lack of a naval variant of the F-22 meanwhile makes deployment from carriers closer to the Chinese coast, which would reduce or eliminate the need for tankers, impossible.
The J-20, though currently perhaps slightly less capable as an air superiority platform than the F-22, has been developed specifically for war in the Pacific theatre - retaining a considerably longer range than the Raptor. In its 2011 Annual Report to Congress the Pentagon described the J-20 as "a platform capable of long range, penetrating strikes into complex air defence environments" - reflecting both its formidable survivability as a fast, high flying and stealth jet and its long range and high payload ideally suited to an offensive role in the Pacific - putting U.S. facilities at considerable risk without a considerable need for tanker support. Coming at under a third of the F-22's cost, and based on a comparison of other Chinese jets to their American equivalents also requiring far less maintenance, there will be many times more J-20 jets in the skies over Asia than there will be Raptors in the entire world - with the Chinese fighter set to be built in considerably greater numbers, spend more time in the air for every hour of maintenance on the ground, and see their deployments concentrated to the Pacific theatre where the Raptors are scattered across the world. As a result it is likely that the J-20 fleet will outnumber the Raptors in the Pacific theatre by an order of magnitude if not more. Combined with highly similar capabilities today and applications of new upgrades at a far faster rate, the J-20 is set to be a more capable, more numerous and better specialised fighter to combat in the Pacific theatre - a possibly decisive game changer in the balance of power which the Raptor can never be.