WASHINGTON - As the convoy of Toyota Land Cruisers and Ford Ranger trucks bumped along the cratered road carved through the mountains west of Kabul, Marine Col. Paul McHale imagined the history of the fabled route through the Khyber Pass.

McHale was riding with Afghanistan's interior minister, who also was thinking of history - the years of rampant corruption at Torkum Gate, where trucks and foot traffic seek entry from Pakistan.

When they arrived at the heavily fenced border checkpoint, the minister met with police officials, while McHale spotted some familiar uniforms and sought out a Marine second lieutenant.

After hearing of the officer's experiences on the frontier, McHale, 57, was pumped.

"I was jealous as hell," he said later. "I realized I'd trade any job I've ever had to be that young lieutenant."

Anything, he thought, to remain in Afghanistan.

"You couldn't find a better enemy than the Taliban," McHale continued. "I can't imagine an enemy more worthy of dying.

"If I was 22 years old, I'd enlist in the Marines and ask for Afghanistan," he said. "It is a place where a young warrior can make a real difference fighting for a noble cause."

McHale was once again such a warrior. Riding in heavily armed convoys through some of the most dangerous territory on Earth, he was teaching Afghan soldiers how to better counter an implacable Taliban foe.

But McHale was only moonlighting as a Marine. In his day job, he is assistant secretary of defense in charge of homeland defense, a senior Pentagon post that puts him in command of about 400 uniformed military, civilians and contractors and a budget of $20 billion.

Despite his retirement from the Marine reserves in 2006, he grabbed hold of one final chance to go to war, signing up for a tour of duty in Afghanistan that thrust him to the front line of the global war on terrorism. McHale fretted that his Pentagon profile made him a high-value Taliban target, and heightened the danger to those around him. But he could not resist.

His six months in Afghanistan was a huge leap from Capitol Hill, where he served three terms as a Democratic House member from Bethlehem, Pa., and from the security of his ornate office on the Pentagon's D Ring.

What McHale brought home from time on the battlefield was a gritty, sweat-stained understanding of the conflict no other senior civilian at the Pentagon can match.

In a recent interview, McHale said that the war in Afghanistan should be "judged on its own merits." At a time when the U.S. role in Iraq inflames many Americans, McHale urges that the United States intensify its focus on a nation where the fight against terrorism isn't burdened by the mistakes and civil discord as it has been in Iraq. McHale insists that the "noble cause" in Afghanistan is winnable and is a fight embraced by most Afghans.

"The challenge in Afghanistan . . . ought not to be merged with the quite different and distinct challenges in Iraq," he said. "The Afghan people have a growing sense of unity. The Afghan people share an overwhelming commitment to freedom and democracy. In Afghanistan, sectarian violence is almost nonexistent."

McHale's assessment is fraught with a sense of urgency. Visiting Kabul last week, Defense Secretary Robert M. Gates was told by U.S. military and intelligence officials that al-Qaeda might be increasing its activities in the country.

McHale described Marines as a perfect fit for Afghanistan, with its rugged terrain and the need for small units to be integrated into the local populace. At his core, McHale - a compact man whose face is etched with weather-worn lines - is a leatherneck.

"You walked into his office and you knew it belonged to someone in the military," said Geoff Plague, who worked for McHale throughout his congressional career.

A Marine sword hung on the wall of his congressional office, and even now, McHale often speaks of being buried in his dress blues. Pete McCloskey, a former California congressman and Marine whom McHale met as a college student, inspired him to enlist and, later, to seek public office.

As a citizen-soldier, McHale viewed elective office as an "honorable" alternative to military duty, though he often said that, given the choice between being either a Marine or a congressman, he'd choose the uniform.

So close friends were not surprised that McHale reverted to military mode when he urged President Clinton to resign during the Lewinsky scandal, and when he later voted for three of four articles of impeachment against the president.

"Clinton was the commander in chief and, as a military man, resigning was what Paul thought he should do," recalled James Wiltraut, who served as McHale's senior adviser.

McHale enlisted in the Marine Corps after graduating from Lehigh University in 1972, and spent two years on active duty. After law school at Georgetown, McHale practiced law for five years in Bethlehem, then won election to the state House of Representatives in 1982, where he served five terms.

In 1991, he resigned his seat after Iraq's invasion of Kuwait, and, as a Marine reservist, volunteered for active duty and served as an infantry officer in the first Iraq war.

Returning home after two years, McHale decided to go back to public office. He won a U.S. House of Representatives seat from the Allentown-Bethlehem area. But during his third term, he decided it would be his last after his young son, Luke, told McHale as he left home for Washington one day: "You've been gone my whole life."

He resumed his law practice, but several years later he came under consideration for a newly created job as assistant secretary for homeland defense.

According to former staff members, McHale had contact with high-ranking Pentagon officials through his work on the House Armed Services Committee and his cofounding of a National Guard and Reserve Caucus in the House.

Several generals recommended him for the post, and their advocacy - and McHale's military service - was enough to win the appointment in February 2003 from then-Defense Secretary Donald Rumsfeld, who normally was not inclined to reward Democrats.

This is the job he was willing to trade with the lieutenant he encountered in the Afghan mountains. From a Pentagon office in an area damaged by the Sept. 11, 2001, attack, McHale supervises the homeland defense activities of the Department of Defense and coordinates with military allies throughout North, Central and South America.

Recently, back from Afghanistan, McHale supervised military assistance in fighting the California wildfires and participated in a three-city mock terrorist drill involving a radioactive "dirty" bomb.

In August 2006, McHale formally retired from the Marines, and was feted with a "sunset" ceremony in Washington. Yet McHale knew then that he was not actually letting go. During a family kayaking trip earlier that summer, McHale decided he would apply for one more combat tour.

In September he was searching a Marine Corps Web site for a post that he might fill and found one in Afghanistan, where he could replace another reserve colonel.

His superiors in the Marine Corps agreed to his request. "Then I discussed it with the secretary of defense," McHale said, and he received permission to take a leave from his position as assistant secretary.

Afghanistan was a good choice, he thought, because of that nation's role in what history calls the "Great Game" - the battle for a geopolitical keystone - and its new significance.

"I was inclined toward Afghanistan because I had read about and admired their warrior spirit," said McHale, who speaks passionately in a painfully earnest manner, peppered with frequent historic and literary references.

On McHale's desk sit copies of The Federalist, Lincoln's Speeches and Writings, and de Tocqueville's Democracy in America. He is a well-read, thoughtful individual who seems almost apolitical in his views.

Although he often speaks to civic groups, McHale is wary of the news media after receiving some painful criticism, terming him a political opportunist, when he left the Pennsylvania legislature to fight in the Gulf War. When he returned to active duty in December 2006, he turned away all requests for interviews.

His job in Afghanistan was to advise Afghan Interior Minister Zarar Ahmad Moqbil, head of the Afghan national police force. When he wasn't traveling around the country with Zarar, McHale commuted by convoy from a room in a military camp in Kabul to an office four blocks away.

In the six years since the United States drove out the Taliban, its mission has evolved from conventional warfare to combat support for the fledgling national army and police force of the government led by President Hamid Karzai.

A resurgent Taliban has been attacking district police headquarters in the south.

"The Taliban's goal is to kill police officers and other municipal officials in these headquarters and undercut the presence and local strength of the Karzai government," McHale said.

For him, this is ground zero for the war on terrorism - trying to defend a relatively new democracy against terrorist attacks. The Afghan police force is undermanned in large part due to a culture of corruption that creates a wide discrepancy between numbers listed on police rolls and those actually carrying rifles.

"You will find many wonderful people in Afghanistan. You won't find many who are saints," said McHale, referring to widespread payroll inflation.

Afghan scholar Barnett Rubin, who teaches at New York University, said that McHale might be downplaying the effects of corruption.

"Every Afghan I know thinks that there is now more corruption in Afghanistan than ever before in the history of the country," he said by e-mail from Afghanistan. "This is a major reason for the government's loss of support."

Last spring, three months into McHale's tour, the Taliban attacked police headquarters in Giro district in Ghazni province. Four policemen were killed, as well as the district governor and his deputy. Zarar told McHale he wanted to go there.

"Zarar always moved to the sound of the guns," McHale said.

Their convoy of Land Cruisers and Ford Rangers was attended by 100 guards, armed with AK-47s, and a contingent of Afghan police.

McHale's job was to advise Zarar on how to anticipate, deter and defeat such attacks, and how to respond once they had occurred. After a four-hour journey, they met with the provincial governor and senior officials in a police station in Ghazni, the men arrayed around the perimeter of a room about 15 feet wide and 40 feet long as if in a jirga, or tribal assembly.

Quickly, McHale understood how the situation had gone to hell.

On paper, 30 police officers were assigned to Giro. In reality, only 15 were on duty. They were attacked by a larger contingent of Taliban, armed with rocket-propelled grenades and heavy machine guns. The more lightly armed police ran out of ammunition during the firefight, according to the provincial governor.

"Giro was a case study in Taliban tactics," McHale said.

"There was not a unified response to the attack, and for that reason the defenders of that government outpost were left without assistance for a long period of time," McHale said.

He concluded that closer coordination between the police and the Afghan army might have saved lives and made that recommendation to Zarar.

"The following week, we put in place initiatives to bring about closer planning between the army and the police, and those initiatives are ongoing," said McHale.

In the ensuing months, McHale better understood that the fight was as much against decades of corrupted payrolls and the purchase of personal loyalties that undermined the effectiveness of the Afghan army and police.

"During the Soviet occupation and during the Taliban period, most Afghans had to struggle to survive, and survival depended on some cunning skills that we might find unethical," he said.

Rubin said the Taliban is not popular, but added that Karzai's weak leadership, the government's inability to provide security, and corruption among high officials afford the Taliban a toehold.

"By any measure, next to no one wants the Taliban back," McHale said. "There is a desire on the part of the Afghan people for the central government to provide better security, stronger economic development, more modern infrastructure and other attributes of a modern society."

McHale left Afghanistan in late June and returned to his old job at the Pentagon Aug. 1. Members of Congress have discussed the wars in Iraq and Afghanistan with him - including Pennsylvania Democrats Joe Sestak, Patrick Murphy and Chris Carney, veterans all - and McHale makes certain to draw a distinction between the two conflicts.

McHale said his own service has made him a passionate advocate among former colleagues for the mission in Afghanistan.

"There may be differences with regard to the proper means by which to bring the war in Afghanistan to a conclusion but, with very few exceptions, I have sensed a continuing recognition that our fight has been both moral and necessary," McHale said.

"If American military forces have ever fought for a noble cause," he said, "it is in Afghanistan."

Contact staff writer Steve Goldstein at 202-408-2758 or slgoldstein@phillynews.com.