SARAJEVO, Dec 9 (Reuters) - Croatia's government on Friday said it would buy French air defence system Mistral for 72 million euros ($75.84 million) as part of the NATO member's efforts to modernise its air force.The decision follows the purchase last year of 12 French Dassault Rafale fighter jets in a deal worth 999 million euros, to replace Croatia's squadron of Russian-made MiG-21 jets that dates from the period of the former Yugoslavia, only a few of which are still operational."The circumstances that occurred with the Russian aggression on Ukraine and the crash of a drone in Zagreb have shown it is important and necessary to adjust priorities and plans for equipping the Croatian army," Defence Minister Mario Banozic told fellow ministers.In March, a Soviet-era reconnaissance drone that carried an aerial bomb crashed in the capital of Zagreb after entering Croatian air space from neighbouring Hungary, without causing any harm to residents.On Tuesday, a two-seater MIG-21 plane crashed during a military drill in an uninhabited area of forest in northeastern Croatia."