Finland signed a formal agreement on Friday to buy 64 US F-35 Lightning stealth fighter jets, in a deal worth $9.4 billion.
This was signed as tensions between Nato, Russia and its neighbours heighten over the build-up of Russian troops near the Ukraine border.
Finland is not a Nato member but shares a border with Russia. As part of the diplomatic dispute around Ukraine, Moscow has demanded its neighbours do not become join the defence alliance.
Finland calls the deal for the multirole Lockheed Martin aircraft a long-term strategic move. The first Finnish F-35s are due to be deployed in 2027.
“The aim is to ensure that Finland's F-35 system has the best possible performance going into the 2030s,” the Finnish Defence Forces said.
The deal includes maintenance equipment, spare parts and training services, the defence forces said. An agreement to buy air-to-air ammunition is due to be signed later in 2022.
Finland's government said the decision to buy the jets, announced in December, was part of long-term plans to boost the country's defences, not a response to the current confrontation between the West and Russia over Ukraine.
“It is part of our long-term planning and has nothing to do with the current situation as such,” Finland's ambassador to the United States, Mikko Hautala, said.
Finnish Prime Minister Sanna Marin said in January that the country has no plans to apply to join Nato, but also retained the right to do so.
Finland, which was neutral during the Cold War, is a member of the EU.
In recent years it has strengthened co-operation with the western military alliance and its defence forces materiel policy is based on all new equipment being Nato-compatible.
Russia has more than 100,000 troops near Ukraine's borders, and western countries fear it is planning an attack.