Slovakia’s prime minister clashed with the defence ministry on Friday over a deal to acquire US-made F-16 fighter jets in what is slated as the NATO member’s biggest military purchase.

The Slovak Ministry of Defence announced on Friday, November 30 that it had signed three Letters of Offer and Acceptance to procure 14 Lockheed Martin-made F-16 jets, munitions, logistics support and pilot and ground crew training, in a deal that was valued at almost €1.6 billion ($1.8 billion) in July.

“All fighter jets are due to be delivered by the end of 2023,” the ministry said.

Hours later, Prime Minister Peter Pellegrini issued a statement saying that the contracts were invalid because they had not been approved by the finance ministry.

“Premier Pellegrini considers the contracts regarding the purchase of F-16 fighters signed earlier in the day by the defence ministry to be invalid for the moment, as the finance ministry still hasn’t approved the deal,” a statement said.

The defence ministry is headed by Peter Gajdos from the hard-right nationalist eurosceptic Slovak National Party (SNS), a junior coalition partner to Pellegrini’s center-left Direction – Social Democracy (Smer-SD) party.

Analysts suggested Friday that the clash was likely rooted in an internal power struggle within the coalition.

A NATO and eurozone member of 5.4 million people, Slovakia is seeking to replace its ageing fleet of Soviet-designed, Russian made MiG-29 fighter jets.

Long-controversial F-16 purchase

Slovakia had been in talks to purchase Gripens from Saab, but Gajdos stalled those discussions and invited other bidders, with the field eventually narrowing in February to a choice between F-16 Vipers and JAS-39 C/D Gripens.

Among its nearest neighbours, Hungary and the Czech Republic operate Swedish-made Gripen multirole jets, while Poland has fleet of F-16s. Slovakia and the Czech Republic have a “joint sky” agreement where the two help protect each other’s air space and could have also shared maintenance and pilot training if Slovakia had chosen Gripen.

In April, the U.S. State Department approved an estimated $2.91 billion sale of 14 F-16 Viper aircraft to Slovakia, along with an extensive list of equipment, support and training. The proposed sale included AIM-120C7 AMRAAM and AIM-9X Sidewinder air-to-air missiles, and Paveway and JDAM guided bomb tailkits.

In July, Pellegrini said the cabinet had accepted a proposal presented by Gajdos to purchase F-16s.

“Slovakia will pay €1.589 billion [$1.8 billion] for 14 fighter jets, pilot training, ammunition and two-year logistical support,” Pellegrini said, Reuters reported.

Gajdos said the U.S. offer was better “in all aspects,” and that it was “the best possible solution.”

According to Pellegrini, the U.S. bid was better on price and in technical terms, the Slovak Spectator reported. He said that, although the initial outlay for the F-16 was several hundred million euro higher than for the Gripen, over their 30-year life the aircraft were less expensive.

That controversial life-cycle cost evaluation by the finance ministry concluded that the F-16 would be eight percent less costly than the Gripen, but Gadjos said at the time that while the U.S. deal was “ready for signature, the Swedish side insisted on the negotiation of details only after a government decision was taken.”

In September Lockheed Martin vice president Orlando Carvalho said that the first four F-16s would arrive in Slovakia in early 2023, contradicting Friday’s defense ministry statement.

Carvalho said pilot training was scheduled to begin in late 2018 or early 2019, and that around 22 pilots were expected to be trained along with more than 150 maintainers.

With reporting from AFP