The Department of Defense’s fiscal year 2021 budget proposal released this week seeks a modest increase in active duty Army end strength. Since the proposed topline for the defense budget fails to keep pace with inflation, some in Congress may face the temptation to pilfer resources dedicated to Army end strength to fund other priorities. A closer look at the Army’s demanding operational tempo (optempo) demonstrates why any cut would be a mistake that reduces readiness and burdens soldiers and their families.

The Army measures the optempo of its units with a ratio comparing the time the unit is deployed versus the time the unit is not deployed. In Army parlance, this is a unit’s “deploy to dwell” ratio.

For active duty units, the Army believes a 1:3 deploy to dwell ratio is ideal. Under such a scenario, for example, for every 9 months deployed, a unit would spend 27 months not deployed.

When an active duty unit has only a 1:2 deploy to dwell ratio, the Army considers this a “redline” for maintaining readiness.

To be clear, when a unit deploys, for example, from Fort Bragg or Fort Hood to another location in the U.S. for training, it is still considered dwell time.

So, in terms of understanding stress on soldiers and their families, the deploy to dwell ratio should be understood as actually painting a rosier picture than reality warrants.

That fact makes the current deploy to dwell ratio for key active duty units particularly concerning.

Active duty Army corps and division headquarters, as well as brigade combat teams (BCTs), combat aviation brigades (CABs), and Patriot battalions, all have an average deploy to dwell ratio below the Army redline of 1:2.

In fact, corps headquarters are currently home on average for less time than they spend deployed. And half of Patriot battalions are at an approximate 1:1 deploy to dwell ratio.

This hectic optempo is not surprising when one considers the number of soldiers deployed around the world.

The Army notes that it fulfills 60 percent of combatant commander personnel requirements. In January, that meant approximately 113,000 soldiers were deployed overseas in over 140 countries. That includes 37,300 in the Central Command area of responsibility (AOR) and 24,600 in the Indo-Pacific Command AOR.

Here’s the problem with such a hectic optempo.

Soldiers utilize time between deployments to take leave, reconnect with their families, and attend Army schools and individual training opportunities important to soldier competence and professional development.

Units use the time between deployments to repair equipment and conduct essential collective training.

When time is compressed between deployments, units are forced to prioritize collective training—sacrificing soldier leave, individual training, and professional development.

America’s soldiers are incredibly resilient and able to endure great hardship to accomplish the mission. But over time, a deploy to dwell ratio below 1:3 takes a toll on soldiers and their families, hurting readiness and morale.

For the current fiscal year, FY2020, the authorized Regular Army (or active duty) end strength is 480,000. Due to successful recruiting, the Army utilized authorities to go slightly above authorized end strength and has now increased its goal for this fiscal year to 485,000 soldiers.

To recognize this progress and facilitate “modest growth of about 1,000 soldiers per year for the next four or five years,” the Army is requesting an authorized active duty end strength for FY 2021 of almost 486,000.

Even with this growth, the active duty force would be significantly smaller than the post-9/11 high of approximately 566,000 soldiers. This reduction matters, because the fewer soldiers there are, the more frequently the rest need to deploy, which reduces deploy to dwell ratios.

Admittedly, growing the active duty to 486,000 will not solve the Army’s deploy to dwell challenges—but it can help. And modestly increasing the size of the active duty over the next few years—without lowering standards—can steadily begin to address optempo challenges.

Optempo concerns are, of course, not the only consideration when determining the optimal size of the Army. Army leaders also look at what is necessary to support the National Defense Strategy and associated war plans.

The Pentagon is working to develop joint doctrine and operational concepts that will inform future force structure requirements. That process and its result will have important implications for the size of the active duty Army.

In the meantime, leaders should ensure that America’s soldiers have sufficient time between deployments to reset and train for the full range of conflicts they may encounter in the uncertain future.

For now, that means supporting a modest increase in the size of the active duty Army.

Any failure to do so—and especially any effort to cut the size of the active duty Army—would only put a heavier burden on soldiers who are already enduring so much to keep Americans safe.