NATO ambassadors have approved a 27-billion-euro ($31 billion) project to overhaul and expand the alliance’s Cold War-era fuel pipeline network, extending critical supply lines to its eastern flank to strengthen defences against potential Russian threats.

Signed on Wednesday by representatives from NATO’s 32 member states, the agreement sets in motion a 25-year infrastructure project to modernise existing distribution facilities and construct new fuel lines across Eastern and Southeastern Europe.

Alliance officials described the decision as an essential move to ensure troops and air fleets maintain high military readiness and reliable energy supplies during potential conflicts.

"The investment will modernise NATO's existing fuel storage and distribution infrastructure," NATO said in a statement.

"It will support new facilities, including pipelines, in the eastern and southeastern part of the alliance and ensure NATO forces have the energy supplies they need for war-fighting readiness."

Coming just weeks after NATO's Ankara summit, where the deal was nearly finalised following intense lobbying, the initiative marks the most significant expansion of the NATO Central European Pipeline System since its creation in the late 1950s.

Established during the Cold War to supply allied forces across Western Europe, the current 5,300-kilometre (3,300-mile) network spans Belgium, France, Germany, Luxembourg, and the Netherlands, supplying fuel to 29 military depots.

Extending the pipeline network eastward addresses longstanding logistical bottlenecks along NATO’s frontier with Ukraine and Russia. Member states in the region have faced mounting security challenges, including repeated air and drone incursions stemming from the war in Ukraine.

Romanian President Nicusor Dan praised the plan on Thursday, describing the pipeline expansion as "essential to reinforce security" on NATO’s eastern edge.

Extending direct fuel infrastructure to eastern nations will enable rapid force deployment and cut reliance on vulnerable surface transport, such as rail or road tankers.

The quarter-century overhaul will incrementally upgrade NATO’s energy grid, ensuring secure fuel delivery to ground and air units stationed across the continent for decades to come.