In a move some are calling a "backdoor draft," the Pentagon has announced it will issue mandatory recalls to more than 5,600 Army troops for deployment to Iraq and Afghanistan. The use of these soldiers from the Individual Ready Reserve is the latest step military leaders are taking to maintain adequate troop strength for our continuing battles in the Middle East. Thousands of service members have had their tours of duty extended beyond the terms of their contracts. "Stop-loss" orders were issued to delay scheduled discharges. And Congress recently approved increasing the size of the Army by 20,000 recruits.

As military and political leaders struggle to address critical troop shortages in the Middle East, they should consider the results of a data analysis just released by the Center for the Study of Sexual Minorities in the Military, of the University of California at Santa Barbara. Our report, which analyzed data obtained from the Defense Manpower Data Center through a Freedom of Information Act request, revealed that the military is losing mission-critical combat and support specialists because of the ban on openly gay soldiers. What is particularly troubling about the results is that the "don't ask, don't tell" policy, which requires the discharge of known gays and lesbians, is ousting troops in the very same occupational specialties as service members who are being involuntarily recalled from civilian life.

The Pentagon's recalls are targeting specialists with needed skills in intelligence, engineering, medicine, administration, transportation, security, and other key support and logistical areas. Under the gay ban, the military has expelled thousands of just such troops: 268 in intelligence, 57 in combat engineering, 331 in medical treatment, 255 in administration, 292 in transportation, 232 in military police and security, and 420 in supply and logistics since 1998. It also booted 88 language specialists (many of them Arabic-language translators and interrogators); 49 nuclear, biological and chemical warfare experts; 52 missile guidance and control operators; and 150 rocket, missile and other artillery specialists.

In certain badly needed specialties, the military could have avoided involuntary recalls altogether if it had not expelled competent gay troops in those fields: It is recalling 72 soldiers in communication and navigation but expelled 115 gay troops in that category; 33 in operational intelligence but expelled 50 gays; 33 in combat operations control but expelled 106. In total, while the Army is set to recall 5,674 troops from the Individual Ready Reserve, 6,273 troops have been discharged for being gay, lesbian or bisexual since 1998. The discharges continue, at the rate of two to three per day, despite alarming reports that the military is stretched dangerously thin and is overtaxing its current forces.

The forced extension of military service comes at great cost to America's troops and its mission. We now depend heavily on reservists and National Guard troops, who have less training, higher stress levels and lower morale. Members of the Individual Ready Reserve are even less prepared and less cohesive, because they have not been training with a unit while out of the service. The "don't ask, don't tell" policy, in short, puts discrimination against competent soldiers above the combat readiness of the entire force.

Early in the current conflict, the Pentagon issued stop-loss orders to maintain troop strength as the nation went to war. But so determined was the military to spare its ranks the mark of homosexuality that the order explicitly excepted gay discharges from the stop-loss, allowing their expulsions to continue. Yet actual gay discharge figures, which have skyrocketed under "don't ask, don't tell," have sagged during the war itself, as they have in every war since World War II. Why? Because commanders in the field -- focused on winning the battles at hand -- have clearly turned a blind eye to the policy. They know what nearly every expert now admits: that when unit cohesion matters most, sexual orientation is the furthest thing from anyone's mind.

It's time to call on Congress, which wrote the current gay ban into law, to put national security before discrimination against patriotic gay Americans ready to serve their country.

The writer is a senior research fellow at the Center for the Study of Sexual Minorities in the Military at the University of California at Santa Barbara and is writing a book on "don't ask, don't tell."