Europe's most exposed stretch of land sits between Kaliningrad and Belarus, and NATO's own planners now think it could be cut off faster than the alliance can agree to defend it.

• Russia already jams and fakes GPS signals across Polish and Lithuanian airspace, which would blunt NATO's precision weapons from the first hour.
• NATO's old assumption of 90 days of warning is gone; Russian forces could reach Riga and Tallinn in 36 to 60 hours.
• Reinforcements depend on rail, but Polish and Lithuanian track widths differ, so tanks must be craned one at a time at a single small Lithuanian yard — a bottleneck Russia could destroy in minutes.
• Most NATO battle tanks are too heavy for the local bridges, and the few usable roads are already mapped and pre-targeted.
• Article 5 does not force members to fight, only to do what each "deems necessary" — a gap Russia could exploit with strikes launched from its own soil.

Outlook: Analysts point to 2028-2030 as the riskiest window, since the standard-gauge Rail Baltica line that would fix the bottleneck is not due until 2030.