(Reuters) - Finland has prepared for decades for a Russian attack and would put up stiff resistance should one occur, its armed forces chief said.

The Nordic country has built up a substantial arsenal. But aside from the military hardware, General Timo Kivinen said, a crucial factor is that Finns would be motivated to fight.

"The most important line of defence is between one's ears, as the war in Ukraine proves at the moment," Kivinen said in an interview.

Finland fought two wars in the 1940s against its eastern neighbour, with which it shares a 1,300-km (810-mile) border.

Once a non-aligned country, it is now applying to join the NATO military alliance over concerns that Russia could invade like it did Ukraine on Feb. 24.

Since World War Two, Helsinki has kept up a high level of military preparedness.

"We have systematically developed our military defence precisely for this type of warfare that is being waged there (in Ukraine), with a massive use of firepower, armoured forces and also airforces," Kivinen said.

"Ukraine has been a tough bite to chew (for Russia) and so would be Finland."

Some 100,000 Finns were killed during the two wars Finland fought against the Soviet Union and it lost a tenth of its territory.

The nation of 5.5 million has a wartime troop strength of some 280,000 with 870,000 trained as reservists. It did not abolish military conscription for males as many other western nations did after the end of the Cold War.

It has also built one of Europe's strongest artilleries and has stocked up on cruise missiles with a range of up to 370 km (230 miles). It spends 2% of its GDP on defence, a level higher than many NATO countries.

It is ordering four new warships, as well as 64 F-35 fighter jets from U.S. defence giant Lockheed Martin (LMT.N).

It plans to order up to 2,000 drones, its own high altitude anti-aircraft equipment and is building barriers on its border with Russia.