Smarting from South Korea’s decision to sideline Boeing’s F-15 Silent Eagle and reopen bidding for a new fighter, the company is now lowering its expectations to capture some — but likely not all — of a forthcoming buy.

Boeing Defense, Space and Security President Dennis Muilenburg said the company is still investing in development of the Silent Eagle and remains in the game for Seoul’s yet-to-be-revamped F-X Phase 3 competition. The original requirement was to buy 60 new fighters to replace aging F-4s and F-5s beginning in 2017. Boeing designed the upgraded F-15 Silent Eagle specifically for South Korea and Israel, which effectively passed on the design when it selected the F-35.

Last month, Seoul set aside a recommendation from its Defense Acquisition Program Administration for the Silent Eagle, designed with conformal fuel tanks, a stealthy weapons bay, fly-by-wire and a digital electronic warfare system. Boeing’s offer was the only one found to be compliant with South Korea’s bidding rules and to stay within the 8.3 trillion won ($7.7 billion) budget. Eurofighter’s Typhoon was disqualified due to a bidding irregularity and Lockheed Martin’s F-35 bid exceeded the budget for 60 aircraft in the F-X Phase 3 competition.

Muilenburg says that South Korea, already an F-15 operator, might be interested in a mixed buy of the Silent Eagle and another competitor, most likely the F-35. “The acquisition that was just delayed was an acquisition for 60 aircraft at the same time … If you are looking at budget constraints, schedule constraints, desires for technology, perhaps a mixed buy or split buy of some sort” could be an option in Seoul, Muilenburg said during an Oct. 10 roundtable with Aviation Week in Washington. “They have some very tough schedule constraints.” With South Korea originally hoping to introduce the new fighter into service in 2016, skeptics questioned whether the F-35 could be ready in time.

Muilenburg argues that for an assured price, an upgraded F-15 can offer Seoul a much-needed capability quickly. “The terminology ‘fifth-generation fighter’ is a convenient marketing tool” for Lockheed Martin, he says, referring to the F-35. “A lot of discussion has gone into all-aspect stealth. I prefer to talk about all-aspect fighters that are not compromised for stealth.” Though the Silent Eagle lacks all-aspect stealth, it is optimized for frontal aspect stealth and features a far superior payload and speed over the F-35, Muilenburg says.

It is clear the F-35 has strong support in South Korea despite the higher cost and uncertainty over schedule pending the conclusion of flight testing in 2016; 15 former South Korean air force chiefs wrote an open letter supporting the selection of the F-35.

In a sense, Boeing’s strategy now in South Korea mirrors what it was in Australia, where the company convinced Canberra to buy additional F/A-18s while awaiting the F-35.

Underscoring the time pressure is a plan for South Korea to assume wartime operational control of forces on the peninsula as soon as December 2015. Washington and Seoul are expected to set a firm date for the transfer next year.

Meanwhile, Muilenburg says interest in upgrades for the F-15 — included those in the Silent Eagle package — remain of interest to international F-15 operators. Customers are able to purchase the upgrades — such as the digital electronic warfare system and radar — without the conformal weapon bay and other improvements aimed at stealthiness.

[Editor's Note: This story was amended to correct a typo