supersonic fighters after 2015. The JAS-39 Gripen was generally accepted as the most effective option owing to the existing infrastructure, the availability of trained personnel and previous good operational experience. However, the background of the existing contract – specifically the broadly discussed issue of alleged corruption – prevented politicians from settling for this quick solution, favouring instead a general tender with more bidders offering such types as the F-16, F/A-18, F-15SE or F-35A. The creation of a non-supersonic air force has also been discussed as an option, owing to the perceived high costs and limited usefulness of keeping supersonic assets in a country surrounded by allied countries (all are European Union members and NATO members, except Austria). In this scenario the subsonic L-159 would become the backbone of the air force. The latest 2011 White Book clearly states that the supersonic fleet is to be continued for the protection of the Czech Republic and for co-operation within the NATO Integrated Air Defence System. Twelve single-seat and two twin-seat aircraft are viewed as sufficient for patrolling the Czech Republic, while 18 can support the sentry role in other NATO countries. A preliminary RFI requested 18 aircraft. The White Book specifies the 12+2 solution, requiring strategic requirements for the supersonic air force to be specified by November 2011. On 16 May 2014, the director general of the Swedish defence and export agency FXM and the Czech deputy defence minister for defence acquisitions signed the "Annex prolonging agreement of lease of the JAS-39 Gripen aircraft", ensuring also the continuous upgrading and increasing the capabilities of these machines. The Swedish supersonic aircraft will equip the Czech Air Force until 2027 with an option for further two years. Czech Defense Minister Martin Stropnický has unveiled plans to replace Soviet-designed military equipment with new weapons and to acquire helicopters and radars for the Czech Air Force, with tenders expected to be launched in 2015. In June 2019, the Czech Defence Minister submitted a contract to the government for the procurement of two C-295 transport aircraft to replace its Yakovlev Yak-40s. On 22 August 2019, Czech Prime Minister Andrej Babiš announced that the Czech Air Force had selected an offer from Bell Helicopter for eight UH-1Y Venom and four AH-1Z Viper helicopters. A contract for the helicopters was signed on 13 December 2019. 2020s In September 2021 Czech Defense minister Lubomír Metnar signed contract with government of