The British government abruptly raised the reservist call-up age to 65 as it moved to strengthen its security posture. It is seen as a sign that Europe's security environment has deteriorated just as fast since Russia's invasion of Ukraine.
The Ministry of National Defense on the 15th (local time) unveiled a defense law amendment that would significantly expand the call-up pool for the ex-service-member-centered strategic reserve. The core of the measure is to extend the upper age limit for reservist call-ups by 10 years, from 55 to 65. In British public health and policy documents, 65 is typically classified as an elderly population.
The post-discharge call-up standby period will also be extended to up to 18 years. Considering that Korea's reservist call-up period is eight years after discharge, the British reserve obligation will become more than 20 years longer than Korea's. Unlike Korean ex-service members, who usually finish their call-up obligation by their early 40s at the latest, British ex-service members could be required to return to active military duty well past age 60.
The reason the British government lowered the bar despite criticism of creating a "grandfather unit" is the rapid deterioration of the security environment. According to British public health documents, those 65 and older are classified as the elderly population. About 19% of England's population is in this age group. Sky News said, "Including people at an age when society expects retirement in the war-readiness manpower pool shows the level of crisis Britain feels."
Call-up criteria were also relaxed. Previously, reservists could be called up only in the event of a national danger, a major emergency, or a direct attack on the United Kingdom. The amendment lowers this to a "warlike preparations" stage. The intent is to reinforce troops immediately if signs of crisis are detected even before a full-scale war breaks out. The Ministry of National Defense and local media projected that the measure will add tens of thousands more to the strategic reserve, currently about 95,000.
This is not simply about increasing headcount; it focuses on securing skilled personnel who can be used immediately in a wartime crisis. The judgment is that a war's outcome depends not on troop numbers, but on transition speed and expertise. In 2022, the United Kingdom made more than 20% of the personnel participating in training support for Ukrainian forces reservists. They trained more than 30,000 Ukrainian recruits over a year, filling gaps in the regular forces.
The Ministry of National Defense did not premise a plan to deploy older reservists into infantry combat. Even if older reservists are newly called up, the likelihood they will pick up weapons and be sent to frontline infantry combat is low. Under the ministry's plan, they will be concentrated in rear support fields that require skill, such as information and communications like cyberwarfare, medical services, logistics, and command staff roles. Defense Secretary John Healey said that day, "We decided to strengthen the reserves so that the valuable skills and experience held by seasoned ex-service members can be used in times of crisis."
Behind Britain's turn to reserves lies a practical constraint on defense spending. The military leadership is struggling with chronic budget shortfalls. Air Chief Marshal Richard Knighton recently told Parliament, "The defense budget is £28 billion (about 49 trillion won) short of plan," adding, "It is difficult to push quickly for everything we want within the budget range currently set."
It takes enormous time and expense to train new regular troops. By contrast, reservists are skilled personnel who have already completed basic training. The cost-effectiveness is high. Assigning older reservists to technical or staff positions can also yield the secondary benefit of concentrating relatively younger, fitter regular troops at the front line.
International pressure cannot be ignored. U.S. President Donald Trump is pressing European allies hard to increase defense spending. Britain has also set a goal of raising defense spending to 5% of gross domestic product (GDP) by 2035. However, expanding defense spending does not immediately translate into more troops. It takes time to train new personnel and increase the regular force. Excluding reserve mobilization, realistic options to strengthen capabilities immediately, as the United States wants, are limited.
Other European countries in the North Atlantic Treaty Organization (NATO), including France, Germany and Poland, are also moving to counter the Russian threat by strengthening reserve forces. Northern European countries, which have relatively smaller populations than major Western European countries, are reinforcing their defense systems by combining not only reserves but also civil defense under the concept of "total defense."
The measure takes effect in the spring of 2027. It will not be applied retroactively to those already discharged unless they agree. The British government plans to pass the bill swiftly in Parliament to modernize the national emergency response system.
Some experts, however, warned that a call-up obligation extending to age 65 could fuel avoidance of military service. A representative of the Royal United Services Institute (RUSI), a British defense think tank, added, "Widening the reserve pool is necessary, but when they are actually called up, a concrete compensation system must support them so they can maintain civilian jobs while fulfilling military duties."