South Korea decided not to select Boeing's F-15SE as the country's next fighter jet Tuesday amid concern the sole-remaining candidate for the 8.3 trillion won (US$7.2 billion) project is not suitable as it lacks stealth features.

The decision, which came in a meeting of the Defense Acquisition Program Administration (DAPA) presided over by Defense Minister Kim Kwan-jin, prompted the government to restart the procurement program from the beginning, further delaying the replacement of the aging fleet of F-4s and F-5s.

Locked in competition with Lockheed Martin's F-35 and EADS' Eurofighter, Boeing was close to winning the deal with a cheaper offer than its rivals. But its fourth-generation aircraft finished in second place behind the F-35 stealth jet in comprehensive assessments, leaving questions over its combat capabilities.

"The committee made the decision through in-depth discussions on the security situation and the combat environment based on assessments of the jets' mission capabilities and prices," DAPA spokesman Baek Yoon-hyung said in a briefing. "The DAPA will promptly restart the project to minimize the security vacuum by consulting related organizations to revise the total budget and requirements."

Boeing expressed disappointment and regret over the DAPA's decision, saying it has strictly abided by every procedure and will wait to hear clearer explanation from them.

According to military officials, the procurement agency insisted on proceeding with the project in accordance with its policy, while the defense ministry opposed the selection process that gave top priority to cost over combat capabilities.

"A majority of the committee members agreed to reject (F-15 SE) and restart the project, taking into consideration the recent security situation including North Korea's third nuclear test and latest aerospace technology development," defense ministry spokesman Kim Min-seok said. "They agreed that South Korean Air Force needs fifth-generation combat jets to keep pace with the latest trend and to deter provocations by North Korea."

A team of officials from the defense ministry, Air Force and acquisition agency will consider various alternatives, including changing the number of jets, extending the funding and combining different types of aircraft, Kim said.

It is expected to take about one year to select the next fighter jet, he added, without giving details on a specific timeframe.

Their rejection on the verge of the final selection illustrates pressure felt by the military and the government to buy 60 jets from the F-15 family with improved features as experts and former Air Force chiefs have expressed concern over the jet's stealth capabilities.

As the F-15 SE failed to get approval at the last minute, the DAPA will restart the procurement program, which is expected to further delay the replacement of South Korean Air Force's aging fleet of F-4s and F-5s. Seoul had initially required a potential contractor to deliver 60 jets for five years from 2017.

The combat-proven F-15 family jet customized for South Korean Air Force is equipped with active electronically scanned array radar and fly-by-wire system, and offers the largest weapons load capacity in the fourth-generation class.

"Silent Eagle is an aircraft that is neither old nor of a paper design," Boeing said in a statement. "SE is an evolutionary design built on a combat proven airframe whose aerodynamic configuration is as optimal today as it was when initially developed."  

Boeing tried to highlight its conformal weapons bay as one of the key radar-evading features, but it failed to quell questions over its capability against F-35, which is originally designed as a stealth jet.

Lockheed Martin and EADS welcomed the decision.

The U.S. defense contractor said it intends to make a bid again if the DAPA puts up another auction. EADS stressed that since it promised to invest 2 trillion won in Korea's fighter jet project, Eurofighter is the only one that can fill the vacuum in Korea's defense strength.