NATO leaders agreed new plans at the alliance’s Vilnius summit last year and are due to receive updates at a summit in Washington that starts on Tuesday, held to mark the bloc’s 75th anniversary.

Following the end of the Cold War, many NATO member countries reduced their defensive capacities, believing Russia no longer posed a threat in the post-Soviet era. That all changed with Moscow’s February 2022 invasion of Ukraine.

A source speaking on condition of anonymity said the requirements, dubbed “regional plans”, would call for between 35 and 50 more brigades. A brigade consists of between 3,000 and 7,000 soldiers, putting the headcount at 105,000–350,000. NATO members could muster this number either by increasing recruitment or by re-allocating existing personnel, Reuters reported.

The alliance’s new strategy to counter the Russian threat remains classified but is known to involve a major policy shift entailing the first major defense plans in 30 years. One security official told Reuters that as a potential frontline state, Germany alone would have to quadruple its air-defense capabilities.

One NATO official told Reuters the military bloc had identified “detailed requirements for troops and weapons needed to defend the alliance.”

“Air and missile defenses, long-range weapons, logistics as well as large land maneuver formations are among our top priorities,” the official told the news agency.

“NATO will likely set more demanding capability targets for allies as we develop forces that can implement our plans and meet the threats we face. We are confident that our deterrence is and will remain strong.”