“From the first metre” is how Nato plans to fight a Russian invasion of the Baltic states.

At the crux of this plan is the “Baltic Defence Line”, Estonia, Latvia and Lithuania’s joint project to fortify a 600-mile stretch of their borders with Russia and Belarus, the most exposed part of Nato’s eastern flank.

The core elements, first announced in January 2024, include 1,000 concrete bunkers – 600 in Estonia – paired with trenches, anti-tank ditches, ammunition depots and supply shelters.

Construction is moving at speed, but estimates suggest it could take a decade to complete. Baltic officials fear they are running out of time.

“Ten years is needed for us to prepare to face the Russian threat. Putin is not going to let us wait those 10 years,” warned Gabrielius Landsbergis, who served as Lithuania’s foreign minister until November.

“The most dangerous time for the Baltics will be immediately after a ceasefire in Ukraine,” he said.

The small former Soviet states are keenly aware that Russia, with its economy already on a war footing, has laid out plans to ramp up military production and send additional troops to their borders in the event of a pause in the war in Ukraine.