How committed is Nato to the defence of the Baltic states? That was the question that Vladimir Putin was indirectly posing, when Russian fighter planes violated Estonian airspace last week.

Nato’s public position is unequivocal: the 32-country alliance will defend every inch of its territory. That commitment is on display at Estonia’s Tapa military base, near the Russian frontier. Tapa — which literally means “kill” in Estonian — was once the site of a Soviet air base. Now it is the main base for the Estonian army and a British-led Nato battle group.

Troops from the Royal Tank Regiment had recently arrived when I visited Tapa last week. Together with a smaller detachment from France, they have an impressive array of firepower on the base — including Challenger 2 battle tanks, the Archer artillery system and Griffon armoured personnel carriers. The British, French and Estonian troops have an integrated command structure and would go into battle together — if there were ever a Russian invasion of Estonia.