Active Duty Military Personnel By Branch:
Army 531,526 (38%)
Marines 193,040 (14%)
Air Force 328,771 (24%)
Navy 331,785 (24%)
Active Duty Military Personnel In Iraq By Branch:
Army 117,100 (64%)
Marines 24,500 (13%)
Air Force 20,700 (11%)
Navy 20,800 (11%)
Active Duty Military Personnel In Afghanistan By Branch:
Army 21,700 (68%)
Marines 3,600 (11%)
Air Force 5,100 (16%)
Navy 1,300 (4%)
Source: The Center for American Progress via Defense Tech.
U.S. Military Iraq Fatalities By Service Branch:
Army 3,063 (including 130 reserves and 452 national guard and 4 civilian DOD) (73%)
Marines 1,008 (including 131 reserves) (24%)
Air Force 52 (including 3 national guard and 2 civilian DOD) (1%)
Navy 97 (including 14 reserves and 1 coast guard) (2%)
(1 civilian DOD not affiliated with any military service excluded)
Obviously, it isn't the Navy's fault that we're at war in landlocked or near landlocked countries with guerilla forces that don't have navies of their own. And, the Army and Marines have taken a heavier share of casulties relative to their number of personnel than the other services in almost every war U.S. war. But, the Army is clearly bearing a heavier proportional burden in the wars in Iraq and Afghanistan than the other services, so the Army needs to have more resources made available to it. Waging war, while we are doing it, shouldn't be business as usual when it comes to providing services with many soldiers deployed in combat zones with resources.
Also, it is much cheaper to grow the Army than it is to grow the Navy or Air Force. Army equipment for an Army unit is cheaper per soldier than warships, and warplanes. While it takes considerable time and expense, it is still much cheaper and quicker to train an infrantryman than it is to train a fighter pilot.
Historically, the United States military has relied upon the draft to quickly swell the ranks of the Army. But, training a modern soldier takes much longer than it did back in the days of WWI and WWII, and political reluctance to draft soldiers has increased greatly since the draft was abolished in the wake of Vietnam.
The nation correctly learned from Vietnam that it doesn't make sense to refrain from deploying national guard members in foreign wars while drafting civilians to serve in the military. But, Iraq and Afghanistan has taught us that we overcorrected. There are high domestic costs to deploying National Guard units, which are needed for disaster response after events like hurricanes and wild fires, as if they were interchangeable with active duty soldiers or reserve troops that don't also have a civilian mission.
National guard troops should be deployed abroad only after all other military personnel resources have been exhausted. And, the nation should also have as an option, the ability to repurpose underutilitized active duty military personnel from other services, something now done only on an extremely limited volunteer basis, before resorting to drafting civilians and parallel with calling in the National Guard to serve abroad.
Furthermore, while it is appropriate to use reserve, national guard, and repurposed soldiers from other military branches to meet short term emergencies, when major military conflicts like Iraq and Afghanistan go one for many years, it is no longer honest to treat the personnel demands that the conflicts place of the military services as emergencies that must be met with back up forces. To the extent that excess force needs can be predicted in time to increase active duty force stengths, those forces should be supplied through increased recruiting for the active duty military.
Right now, with a third of the U.S. Army deployed in Iraq and Afghanistan at any given time (which is close to the greatest extent to which the Army is capable of deploying soldiers in combat on a sustainable basis), additional foreign bases to maintain, and the nation's available reserve and national guard resources all but exhausted, the U.S. military is ill equipped to respond to any contingency that requires any significant number of Army troops.
The planned withdrawal of most U.S. troops from Iraq in the coming months will ease the burden and give the Army some time to recover, even with U.S. deployments in Afghanistan projected to increase. But, continuing to keep the Army so strapped, limits our options militarily in any conflict anywhere in the world.