By top Pentagon order, from now on only Humvees that carry some degree of armored protection will be allowed to leave secure U.S. encampments for patrols and convoys on the often-mean streets of Iraq.

The new edict comes as a Scripps Howard News Service analysis has found that more than 1 in 4 of the 1,450 deaths of American troops in the war have been associated with Humvees. Hundreds more soldiers have been wounded in them.

No other piece of war equipment _ including helicopters, planes, trucks and other combat transport _ carries such a deadly record. The casualty count of at least 387 includes 75 troops who died in Humvee accidents; that is more than the 67 GIs who have perished in aircraft crashes in the Iraq war.

By far, though, it is combat that has been the most dangerous. About 70 percent of Humvee casualties have come from insurgents wielding roadside bombs, rocket-propelled grenades and other weapons, the analysis showed.

Using the publicly available data on which the Scripps analysis was based, it cannot be determined how many deaths occurred in unarmored or lightly protected Humvees, which were not originally designed for combat use.

And, as the Jan. 31 deaths of three Marines south of Baghdad showed, even the most well-fortified Humvee can be eviscerated by a well-placed explosive.

But troops and their families have charged that many of the deaths and injuries could have been avoided if the Humvees, made with fiberglass and aluminum, and equipped with fabric roofs and open sides, instead were made with steel.

As few as 2,000 of the fleet of about 10,000 Humvees in Iraq were armored in some way when the war began nearly two years ago, the Pentagon has acknowledged. Commanders never envisioned Humvees as combat vehicles, expecting instead to use them as transport behind the lines.

After an enemy insurgency wielding improvised bombs took root in mid-2003, a rising chorus of complaints has come from lawmakers on Capitol hill, frustrated reserve troops and anxious families, who told of troops salvaging scrap from junkyards to weld onto their Humvees themselves.

In response, the Pentagon triggered a wholesale push to produce more armored Humvees and kits containing steel reinforcements that can be attached to vehicles already in the war zone.

Last fiscal year, the Pentagon put in a $1.2 billion order for an additional 6,655 armored Humvees, on top of the 3,700 already being built. On Monday, the White House asked Congress for another $3.3 billion to add armor to trucks and to buy more armored vehicles.

In all, about 19,000 Humvees are in use now in Iraq. The Pentagon says 75 percent are armored in some way, although critics charge that as many as half are equipped only with the "Mad Max"-like protection that troops are attaching themselves.

After taking heat from a National Guardsman in December over the lack of armored vehicles, Defense Secretary Donald Rumsfeld ordered earlier this month that, by Tuesday, all Humvees and other vehicles in Iraq must have some degree of armored protection.

Only those that have been upgraded will be allowed to leave U.S. bases on combat patrols or convoys. Trucks, too, must have armor to hit the roads outside the secured areas.

"There will not be a vehicle moving around in Iraq anywhere outside of a protected compound that does not have the appropriate armor," Rumsfeld said Feb. 3.

Meanwhile, the accident toll for troops in Humvees continues. On Sunday, three soldiers died north of Baghdad after an armored Humvee rolled over into a canal. One of the three, a staff sergeant from Dyess Air Force Base in Texas, died when he tried to rescue the others.

In all, 21 U.S. troops have drowned when their Humvees tumbled into rivers, canals or drainage ditches.

(Reach Lisa Hoffman at hoffmanl(at)shns.com)