Past South Korean air force generals lined up against the F-15SE:
South Korea's 15 former air force chiefs have signed a petition opposing the selection of Boeing Co's (BA) F-15 Silent Eagle for the country's 8.3 trillion won ($7.64 billion) fighter jet program, one former chief said on Thursday, saying the plane lacked the cutting-edge stealth capabilities of more modern fighters. ...
"Like the United States and Japan, we need F-35s as fifth-generation aircraft. We can wait another one or two years, looking ahead 40 years, with the finally selected fighter jets," Kim told Reuters, referring to any delay if the current process is cancelled.
The "F-15SE is still a paper airplane under development based on 1970's models, which raises lots of questions on the effectiveness" of upgrading the F-15 platform, the statement said. "Japan recently bought 42 F-35s and the crucial weapons system to deter North Korea's threats is a stealth fighter," it added.
If South Korea believes they need fully stealthed planes to handle China, they should say so. The idea that South Korea needs a fully stealth aircraft to deal with North Korea's air force is nonsense, if that is what they mean.
If the generals mean they want fully stealthed aircraft to have the capability to strike North Korean nuclear weapons targets, that's also problematic for a small country. Remember, the F-35 is stealthy against radar--not invisible. If the South Korean generals think the F-35 can silently destroy North Korea's nuclear arsenal, I think they are mistaken.
North Korea no doubt has sympathizers or agents around South Korea's air bases. They'll see stealth planes take off.
If South Korea's entire air force goes up, North Korea knows a war is coming. If just the stealth planes go up at first, North Korea will know that only really critical targets are in danger. Probably their nuclear stuff. So North Korea can figure the likely attack avenues and just throw up lots of old-fashioned anti-aircraft shells in the path hoping to get lucky. And they'll duck, of course.
Or use 'em before they lose 'em.
If North Korea initiates a war, no doubt special forces will make those stealth planes and the runways where they are based a prime target. And South Korea won't be able to afford as many F-35 planes as they can F-15SE aircraft.
Face it, for a really effective attack on North Korea, America is needed. If South Korea wants this capability in-house, by all means plan to buy enough F-35s down the road for a small squadron just to pose the threat to North Korea (and leverage American help by having the capability to try on their own).
But other than an anti-nuclear mission, South Korea needs numbers and even frontal-only stealth aircraft have the capacity to deal with non-stealthy planes and hide long enough from even fully stealthed planes--which China apparently does not have in near-term development.