Indianfighter said:Anyway, it is unlikely that the US is "very interested" or "worried" by J-10's development.
The reason is that many small or developing nations make fighter jets nowadays, like China, India, Brazil, Pakistan, Israel, Iran, Taiwan, South Korea etc.
Many more nations make local versions or licenced copies of Russian, Chinese or other western jets like Egypt, Turkey, North Korea, etc.
The appearance of 4th generation fighter jets is fast becoming a norm rather than an exception and every A,B,C nation has MiG-29s, F-16s, Su-27 or Su-30 Flankers, F-15s etc.
The US simply cannot spend time speculating or "worrying" about every new entrant like the J-10, FC-1, T-50, or Azarakhsh.
When a new fighter-jet is announced, the Pentagon just briefs the President on the generation of the fighter, its rough capabilities and assures him that the JSF and F-22 are superior to these jets, and the US airspace and other interests are safe.
I have to agree that the US doesn't worry about every new 4th gen fighter, as you state, but I do believe there are many US tacticians very interested in the J-10. The FC-1 is less capable and therefore less of a worry, the T-50 was developed by SK with the help of Lockheed and is a trainer/light fighter--so no worry there, and most of the other ongoing projects also do not warrant much worry in terms of there comparitive performance or the nations developing them.
The J-10, however, has the potential to rival any western 4th gen fighter, and since it will be decades before the US is fielding only 5th gen fighters, believe me, there are plenty in USAF and USN who are not worried, but definitely interested. The other obvious consideration here is that the Pentagon views China as a potential threat, that is, there is a real possibility within coming decades that some sort of military conflict could arise with Taiwan as the flash point. So US military tacticians have a real interest to know the capabilities of the not just the J-10, but other aircraft in China's inventory like Su-30s. Obviously the USAF was happy to see how India's Su-30s performed given the opportunity.
So to sum up, I don't think the pentagon is worried about the J-10, but rather it is their job to evaluate possible foes in regards to an airplane's capabilities and the tactics used in order to know what to expect. And as I stated, the J-10 has the potential to rival many of the US fighters it would face in a confrontation.