Al-Qaida fighters in mountainous eastern Afghanistan are locked in a bloody and often fierce battle with U.S. and other coalition forces. American warplanes are pounding the well-entrenched terrorists, but allied ground troops are pressing forward in a dangerous advance that has already seen several U.S. and allied Afghan deaths.

It was just a slip of the tongue in an expression of sympathy to the families of the latest American battlefield dead. But instead of referring to the war in Afghanistan, General Tommy Franks referred to another country and another war.

"Our thoughts and prayers go out to the families and the friends of the service members who have lost their lives in our ongoing operations in Vietnam," he said.

Later, at the end of a news briefing, a reporter called the General's attention to his error. The commander of U.S. forces in Afghanistan moved quickly to set the record straight and to shoot down any notion that there are parallels between the fighting in Vietnam and the conflict in Afghanistan.

"Vietnam was a long, long time ago, and not at all like what we're seeing now," he said.

Vietnam became what most critics dubbed a "quagmire", a word no one watching the Pentagon is even close to using to discuss the ongoing operation in Afghanistan, now only five months old and involving just a few thousand U.S. ground soldiers.

But as American casualties mount, some observers are wondering about possible parallels to another conflict, the one in Somalia, where the deaths of 18 U.S. soldiers in just a single battle led to a public uproar and a quick political decision to withdraw all remaining American forces.

Defense Secretary Donald Rumsfeld says America's enemies in the current war on terrorism certainly remember the Somalia phenomenon. But he says the United States does not intend to let al-Qaida succeed.

"The leadership of al-Qaida stated from the outset that their intention was to kill enough Americans so that we would flee and leave the country over to them, and that they had a series of terrorist attacks planned to create an environment that was sufficiently inhospitable that we would leave the country," he said. "And we found information to that effect. It's been said on videotapes. And so we know what their strategy was, and we don't intend to let them succeed with it."

There is no doubt U.S., Afghan and other coalition forces are locked in the stiffest fighting of the war to date. Die-hard al-Qaida and forces described as non-Afghan Taleban who are believed to include Chechens and Uzbeks appear to be fighting to the death in the mountains of eastern Afghanistan south of Gardez.

While American casualties are the highest of the war so far, al-Qaida casualties are even higher, according to the Pentagon.

But more U.S. casualties seem inevitable. Mr. Rumsfeld cautions this is unlikely to be the final battle in a war that he says is global in reach, a war against terrorists.

The Bush administration appears poised to pursue the war for years if necessary. As Mr. Rumsfeld put it this week, "there must be no safe harbor for terrorists. It's a threat that cannot be appeased. And it cannot be ignored."