BRATISLAVA, Slovakia  — The first four of 13 Soviet-era MiG-29 fighter jets that Slovakia decided to give Ukraine have been safely handed over to the Ukrainian air force, the Slovak Defense Ministry said on Thursday.

The ministry said the warplanes were flown from Slovakia to Ukraine by Ukrainian pilots with help from the Slovak air force, Ukrainian personnel and others.

“I thank (all) involved for a fantastic professional job,” Defense Minister Jaroslav Nad said.

The ministry said the remaining MiG-29s will be handed over to the Ukrainian side in the coming weeks. It said it will not provide any additional details until they’re safely in Ukraine.

On Friday, the Slovak government approved a plan to give Ukraine its fleet of 13 Soviet-era MiG-29 fighter jets, becoming the second NATO member to heed the Ukrainian government’s pleas for warplanes to help defend against Russia’s invasion.

Slovakia grounded its MiGs in the summer due to a lack of spare parts and expertise to help maintain them. Fellow NATO members Poland and the Czech Republic stepped in to monitor Slovak air space.

Slovakia previously signed a deal to buy 14 U.S. F-16 Block 70/72 fighter jets, but delivery was pushed back two years with the first aircraft to arrive in early 2024.

The Slovak Defense Ministry said Wednesday the United States has offered Slovakia 12 new military helicopters as compensation for the fighter jets the European country is giving to Ukraine. Under the offer, Slovakia would pay $340 million for the Bell AH-1Z attack choppers in a deal worth about $1 billion. U.S. foreign military financing would cover the other $660 million,