In the four years since the terrorist assaults on the World Trade Center in New York and the Pentagon near Washington, at least two distinct changes in the realm of security have taken place, one that seems to have escaped notice, the other all too evident.

The first is that Muslim extremists have shifted their destructive aim to other Muslims and, to a lesser extent, to Western targets such as London and Madrid away from the United States. There have been no extensive terrorist attacks on the U.S., but Americans cannot be complacent, as surely out there somewhere a terrorist is planning an assault that could be as horrific as that of 9/11.

The daily deaths of American warriors in Iraq and Afghani-stan grab the headlines, but by far, the greater number of victims of terror are Iraqis, other Arabs and other Muslims in the swath of Islam stretching from Morocco through Saudi Arabia to Indonesia. They are the innocent victims being blown up by car bombs, slain by suicide bombers and assassinated in the dark of night.

Sadly, few Muslim leaders anywhere have spoken out to plead for an end to this slaughter. They have been quick to criticize the U.S. for pursuing insurgents in Iraq and Afghanistan but have been strangely mute in condemning Muslim terrorists for murdering their co-religionists.

Why the apparent shift in targeting? No one knows, because Osama bin Laden and his lieutenants in al-Qaida don't announce their strategy on al Jazeera, the Arab TV network. Presumably, the arrest or killing of many of those leaders by the U.S. and its allies, the disruption of terrorist finances and logistics and the threat of U.S. retaliation have deterred some attacks

At the same time, President Bush's "global war on terror," despite some successes, is sputtering. The U.S. remains vulnerable to terrorist attack with ordinary explosives, chemical and biological weapons, and even a crude nuclear device.

The dithering, disorganized response to Hurricane Katrina is evidence that the U.S. is not prepared for a similar but man-made battering. The lessons that terrorists may have learned from the natural disaster along the Gulf of Mexico can only be speculated upon.

Most of all, the American people have not been mobilized for the complicated and convoluted war on terror. Airport and airline security have been tightened, albeit superficially, but little more has been done to energize Americans even though 9/11 is still fresh in their minds.

It may seem contradictory to note that there have been no large-scale terrorist assaults on the U.S. since 9/11 but to contend that Bush's war on terror is faltering.

Consider, however: The president blundered into Iraq with no plan except for a swift military victory, which the forces in the field accomplished handily. Beyond that, his administration has shown no understanding of Iraqi history or culture, no concept of Iraqi politics other than the oppression of Saddam Hussein, no ability to persuade Iraqis and other Arabs of America's good intentions.

Instead, Iraq has become a quagmire, like Vietnam, and Bush, like President Lyndon B. Johnson, seems neither to have the will to mobilize the U.S. to crush the insurgency nor the capacity to find a graceful way out. Americans continue to die by the day and taxpayer dollars disappear down a rathole, draining away resources that could have been used elsewhere to fight terror.

In particular, poll after poll have shown that Americans are not mentally and emotionally engaged in the war on terror but rather are going about their lives almost as if it didn't exist. The president took a five-week vacation, the Congress dispersed for the summer, business and labor and academia have carried on without breaking stride.

For the most part, the only Americans affected by the war have been those in the armed forces, the military reserves called to active duty, and the National Guard units that have been sent to the front. And especially their families.

Writer James Webb, who served in the Marine Corps in Vietnam, has a scene in his searing novel, "Fields of Fire," in which a Marine sergeant returns to Vietnam for a second tour and tells his lieutenant that no one back home seemed to know there was a war on. "It's like nothing really happened, except to other people," the sergeant says. "It isn't touching anybody except us."

Change Vietnam to Iraq and the war on terror and the scene continues to illuminate.

Richard Halloran is a Honolulu-based journalist and former New York Times correspondent in Asia.