Even as West African peacekeeping forces began landing in Liberia, the calls for American troops continued. "You Americans alone are the only people who can help us," a fighter with the Liberian president's anti-terrorism unit told The Washington Post.

Yet the fact that our soldiers won't be coming home from Iraq on time underscores the reason we shouldn't rush to join the Nigerians and others deploying to Liberia: Our military, strong as it is, is stretched almost to the breaking point. Adding another deployment at this time, however well intentioned, would be a serious mistake.

America's armed forces are being used too extensively. We have the war on terrorism, operations in Afghanistan, fighting in Iraq and peacekeeping in the Balkans. Some forces must be held aside in case North Korea starts a war. And this is atop our usual peacetime responsibilities, such as deterring large-scale aggression in vital regions, maintaining alliance commitments and ensuring access to the high seas.

This is unsustainable -- and it can't be fixed until we focus our military resources on missions that are vital to the nation. Specifically, we must field a force able to 1) fight the war on terrorism, which often means fighting with little or no warning in unexpected places, 2) deter aggression against U.S. interests and allies and 3) bolster homeland defense. Non-vital missions such as Liberia must wait.

Adding manpower may seem like a sure way to fill this "capabilities gap," but there are several reasons why it's not the best way to solve the problem. For one thing, people are expensive. Only about a third of the defense budget is spent on weapons; most of the rest goes to personnel and operational costs.

Second, it can be a great temptation for political leaders. A perceived excess of manpower leads them to deploy forces on operations that have little or nothing to do with U.S. national security. After the Cold War, this perception arguably led to heavy U.S. involvement in peacekeeping efforts in places such as Haiti, Somalia and the Balkans.

We also should remember that adding troops doesn't necessarily mean that we can engage in widespread peacekeeping. How they're trained makes a big difference. A force trained and equipped for the Cold War, for example, regardless of size, would be inappropriate for the war on terrorism.

But even if we do wind up adding more troops, we should take steps to ease the stress we're putting on today's force. Among them:

• Reduce Balkan peacekeeping commitments and resist similar deployments.
  Approximately 8,000 U.S. troops are deployed in the Balkans. This, though, is like having 24,000 troops out of service, because for every troop on the ground, one is preparing for deployment and another is recovering from deployment. These missions may give troops some real-world experience, but they still aren't training for combat, and they aren't available to contribute to the nation's other vital needs. Deploying troops to places like Liberia would only exacerbate these problems.
  
  
• Give uniformed service members fewer non-warfighting responsibilities. Congress limits the number of active uniformed personnel in each service (currently about 1.4 million). Every service member in a non-warfighting role is one less soldier in the fighting force. Obviously, we need some uniformed personnel for certain non-warfighting missions, but those activities should be limited. Defense Secretary Donald Rumsfeld has identified 300,000 positions that civilians could fill. Congress should let the Pentagon begin shifting its resources toward its core responsibility -- defending vital U.S. interests.
  
  
• Invest in high-demand assets. The U.S. military has neglected to invest in many of the capabilities now in the highest demand. These include special operations units, reconnaissance, military police, units that specialize in chemical and biological agents, Patriot anti-missile batteries, electronic warfare, and in-flight refueling aircraft. The United States also needs more sealift and airlift capability. Bringing supply and demand of these critical assets into balance would improve both the efficiency and capability of the military.

We may indeed need more uniformed personnel to meet all of our defense needs, especially if we're going to stop depending so heavily on our reserves. But let's first start using those already in uniform more efficiently.

By making smart investments and freeing wasted resources, we can ease the strain on our armed forces and leave them better prepared to fight and win America's wars.

Jack Spencer is a policy analyst at the Davis Institute for International Studies at The Heritage Foundation.