The Czech Republic’s government has signed an agreement with the United States to acquire 24 U.S. F-35 fighter jets as part of a deal worth about $6.6 billion, the biggest single purchase for the Czech military

Czech Defense Minister Jana Černochová and U.S. Ambassador Bijan Sabet signed a memorandum of understanding for the deal.

The Czechs also signed a letter of offer and acceptance, the final step in completing a contract between the governments, the Czech Defense Ministry said.

“By signing this intergovernmental agreement, our country and also our army enter a new era,” Černochová said.

The Czech government approved the deal in September.

The first of the 24 fighter jets should be delivered in 2031, with the rest by 2035.

The American aircraft will replace the 14 JAS-39 Gripen fighter jets from Sweden that are currently used by the Czech army.