Ten years ago today, less than a month after the 9/11 attacks, U.S. air assaults on al-Qaida terrorist camps and Taliban military installations in Afghanistan began what is now the longest war in this nation's history.

Eighteen months later, on March 20, 2003, U.S. forces invaded Iraq.

Since then some 1,700 U.S. military pesonnel have been killed in Afghanistan and nearly 4,500 in Iraq. A recent Brown University study calculated the financial cost of the war on terror at $3.7 trillion and counting.

Increasingly, doubts about the value of spending so much blood and treasure are being raised not just by U.S. citizens but by post-9/11 military veterans.

A survey released this week by the Pew Research Center found only about half the veterans thought either war was worth the costs, and most believe this country should be focusing more on domestic problems than on foreign affairs.

These views reflect growing disenchantment with the U.S. military involvement.

Last year President Barack Obama announced the end of combat operations in Iraq and is on track to pull troops out by year's end. Some 98,000 U.S. troops remain in Afghanistan, and the president plans to send 10,000 home this year along with 23,000 more by next September.

Despite the complex dynamics of the U.S. role in such an unstable but strategically significant part of the world, the goal must be disengagement. The growing uncertainty about the value of the wars, most notably among the veterans of the post-9/11 era, reflects the eroding public support.

Americans, including this newspaper, overwhelmingly supported a war against Afghanistan immediately after the 9/11 terror strikes in pursuit of the architects of that attack. Those perpetrators are now by and large dead, and the mission murkier.

The Iraq invasion was a terrible mistake from the start.

"These wars, this time period, has been unique in our history," said Paul Taylor, one of the authors of the study of veterans' opinions about the conflicts.

Perhaps veterans have stronger views on the wars because they and their families alone have personally sacrificied. Mr. Taylor noted that the views of the wars in Afghanistan and Iraq are different from those during such major conflicts as World War II and Vietnam because the United States now relies on a volunteer military instead of a draft. Americans have even been insulated from the cost, with no tax increases to pay for them, only a mounting debt.

"This has been the longest period of sustained conflict in our history and the fight has been carried by the smallest share," he said.