A sweating man wanders into a crowd and blows himself up, leaving a dozen bodies lifeless on the street. A few blocks away, a car bomb pulverizes an armored Humvee, killing two U.S. soldiers and 14 civilians.

The kind of anonymous insurgent violence that is convulsing Iraq has migrated 1,500 miles east to plague Afghanistan five years after the U.S.-led invasion that toppled the Taliban regime.

CountryWatch: Afghanistan

The prospect of a second downward spiral -- though so far Afghanistan isn't nearly as violent as Iraq -- has experts worried that Western militaries don't have an effective strategy for these irregular wars.

"One Iraq is bad enough," said Bruce Hoffman, a counterinsurgency expert at Georgetown University. "Given that our two main theaters of operations aren't going well, one has to question how well the U.S. understands counterinsurgency."

The reborn Taliban acknowledges that it has adopted the suicide bombings, beheadings and remote-controlled bombs of the Iraqi insurgent movement. Nearly 200 civilians have been killed in suicide attacks this year that look all too much like the wave of bombings sweeping Iraq.

"We're getting stronger in every province and in every district and every village," said Qari Mohammed Yusuf Ahmadi, who calls himself the Taliban's spokesman for southern Afghanistan. "We don't have helicopters and jet fighters. But we're giving America and its allies a tough time with roadside bombs, suicide attacks and ambushes. Our Muslim brothers in Iraq are using the same tactics."

Resemblances to Iraq don't stop there. Taliban public relations teams videotape attacks and post them online, an uncharacteristic venture into modern technology for a Muslim fundamentalist group that once banned cameras and computers.

The West's military strategy in Afghanistan also resembles that in Iraq.

Just as critics say Washington did not send enough troops to Iraq before the insurgency took root, analysts fault the U.S. for failing to press its advantage in Afghanistan in 2002 and 2003 when the Taliban were all but vanquished.

Meanwhile, Afghan observers say the same harsh U.S. tactics, decried in Iraq for causing civilian casualties, have helped the Taliban recruit new fighters.

But unlike Iraq's insurgents, the Taliban has ready sanctuary and support just outside their battle zone, in the border areas of Pakistan.

"There will be no end to this insurgency until its sanctuaries and external support are addressed," said Christopher Alexander, the deputy head of the U.N. Assistance Mission in Afghanistan.

The U.S. military estimates about 6,000 Taliban and other insurgent fighters operate in Afghanistan, many from bases in Pakistan. Yusuf Ahmadi -- who spoke by satellite phone from an undisclosed location and whose exact ties to the militia's leadership are unclear -- put the figure in the tens of thousands.

The Taliban comeback, while focused on the volatile south and east, has begun to hit Kabul. The mountain capital's tree-lined boulevards are now scarred, like the streets of Baghdad, by garlands of razor wire, towering blast walls and impromptu police checkpoints.

There's little indication that Iraqi insurgents are joining the fight in Afghanistan or giving the Taliban direct aid, although a few Arab and Chechen fighters mingle in Taliban ranks.

But even without much personal contact, the Taliban has learned from Iraq's insurgency. Web sites explain the insurgent's art: everything from concealed rocket launchers to roadside bomb-making.

"We're not saying they're getting direct support from Iraq," a U.S. military official in Afghanistan said on condition of anonymity due to the sensitivity the information. "They've evolved by adapting their tactics. They've seen the value of the suicide bomber in Iraq. For them, it's a very cheap and effective weapons system."

The U.S. and NATO military response in Afghanistan also has nuanced differences from Iraq. U.S. warplanes drop 10 times more bombs in Afghanistan than they do in Iraq, and a few U.S. and NATO troops live off base in village houses, a strategy rarely attempted in Iraq.

But most of the allied war efforts looks similar. In both places, troops cordon off villages and search homes. They employ billions of dollars in technology -- things like signal jammers and mine-clearing vehicles -- to find and disarm roadside bombs. They operate from bases nearly identical in appearance, with troops living in tin trailers barricaded by dirt-filled metal baskets.

The Afghan war is still far smaller, occupying just 40,000 allied troops -- a quarter of those in Iraq -- and suffering a fraction of the casualties. But for individual soldiers serving in mountainous Taliban lands like Zabul province, the dangers feel the same.

"I know Iraq grabs a lot of headlines. But there's still a war going on over here," said Lt. Col. Steve Jarrard, 46, of Johnson City, Tenn., based in the hard-bitten southern town of Qalat. "I really hope we're doing the right thing over here."

Right now, it's too early to tell the result of major U.S. and NATO offensives aimed at crushing the Taliban.

"In three to six months you'll see a noticeable effect," said NATO spokesman Maj. Luke Knittig. "But you're talking two to five years before seeing a defeat of the insurgency" in southern Afghanistan.

Click here to go to FOXNews.com's Afghanistan Center.