NATO will need 35-50 additional brigades to implement plans to defend against an attack from Russia.
According to secret plans, the brigades will consist of 3,000 to 7,000 troops.
The creation of 35-50 new such units could become a major problem, Reuters writes, citing military sources.
NATO leaders at a summit in Vilnius last year approved the alliance's first major defence plans.
The new agreements are planned to be translated into specific military requirements.
Presumably, alliance military planners have identified troop and weapon requirements to defend NATO.
Among the top priorities are, among other things, air and missile defense, long-range weapons, and large ground maneuver formations.
It is not yet clear where NATO allies will get additional personnel for 35-50 brigades.
Soldiers may be transferred from other parts of the Armed Forces or they will be recruited additionally.
NATO has previously been concerned about Russia's secret operations on the bottom of the North Sea.
