It's all too easy, as the water pumps churn and troops move throughout New Orleans, to ask: "What took so long? Anyone watching cable news could see what needed to be done."

If only it were that simple.

It's one thing to witness disaster on the nightly news, another to deal with the realities on the ground. New Orleans has experienced a nuclear bomb, absent mushroom cloud and radiation. It looks like the Third World. The wind, storm surge and flood washed away everything that makes a modern city and left a mass of desperate people, desperately difficult to reach.

Estimates of the numbers stranded ranged up to 200,000. Meanwhile, much of the city is under water. The storm all but wiped out power, communications and transportation. And there are few unobstructed ways in or out.

And unlike New York after 9/11, there was no place to turn for immediate help. Major cities surrounding the Big Apple could quickly pitch in, over intact bridges, roads and waterways. The small communities around New Orleans had little extra capacity before the storm. Now they have their own problems.

Where was the military? If the armored brigade from the Louisiana National Guard had been at home instead of Iraq, they might have mattered little. Many soldiers might have been victims or their equipment damaged. They would still have had trouble getting to the scene. And armored forces lack the right stuff - like lots of trucks, boats, and helicopters. In large-scale disasters, state guards always require outside help.

New Orleans needed a national response. And the nation was ready to respond. The problem was not a lack of resources, will or organization. The problem was how to get it to people.

And every aircraft, vehicle, and team sent in requires support, just like the victims - no trivial challenge. In fact, one common problem is that there are good-natured efforts to send so much help, whether it is asked for or not, that it chokes the capacity of the emergency managers to coordinate or care for all the responders. Ironically, this puts more lives at risk and actually slows aid delivery.

The notion that the dire needs of the city could be addressed quickly under impossible conditions is simply ludicrous. It would be irresponsible to gauge the national response solely by the speed with which resources are brought to bear in the first days. How soon assistance arrives is dictated by reality.

Of course, we could have poured troops in before Katrina hit, propositioning aid and evacuating the poor. But that it is just unrealistic. Evacuating a city is a monumental decision. Tracking the unpredictable path of a hurricane means you get, at best, a few days notice to make the call. Then, with scant time as hundreds-of-thousands are clogging the roads out, how do you send masses of vehicles in with troops or supplies?

And sending in troops involves two big risks: The storm could veer into the staging area, making them casualties, or change course, leaving troops poorly positioned to respond. Staging for a hurricane is a Hobson's choice.

It is hard to get very far ahead of a storm. It's in the chaotic aftermath that you struggle to learn the extent of the damage and the capacity to move aid.

It is also hard to believe that massive amounts of aid could have gotten there that much faster. We'll see. That determination will require dispassionate, factual analysis, not emotional or opportunistic Monday-morning quarterbacking based on news reports and press conferences.

For now, here's what we can say about the challenge of New Orleans: This is the kind of crisis the nation must be prepared to tackle - a disaster that exceeds the means of state and local governments. It is a fair test for the new Department of Homeland Security and the military, and for our efforts since 9/11.

We should learn from this tragedy the quality of the leadership, resources and programs we need to meet catastrophic disasters - either natural or manmade. We should, however, temper expectations with realism.

There is also little question that we need a greater national capacity to respond to catastrophic disasters. Fair issues: Did we do the best with what was available, have we gotten better since 9/11, and what are the next steps?

Beyond playing the blame game, we need to rethink whether we're truly doing all the right things. Grants that dole out wads of money with scant regard to national priorities won't do. Today, all the fire stations in New Orleans lie under water, as does much of the equipment bought with federal dollars.

Only a national system - capable of mustering the whole nation, built by meeting the highest national priorities first - can respond to disasters on the scale of Katrina.