Hilferty said U.S. forces are now involved in what he called a "small-scale air assault" in southern Afghanistan, but gave no further details.
Our correspondent in southern Afghanistan says the spring offensive actually began in earnest earlier this week. And he reports today of seeing more than a dozen suspected militants -- blindfolded and handcuffed -- being taken by the U.S. military to a detention facility in Kandahar for questioning.
The spring offensive -- codenamed Mountain Storm -- is believed to be the largest in Afghanistan since Operation Anaconda two years ago near the southeastern border with Pakistan.
But based on deployments observed by RFE/RL in recent weeks, two major differences are apparent.
Operation Anaconda was a localized mission led by conventional U.S. ground troops and supported by a relatively small number of Special Forces. By comparison, the plans on the Afghan side of the border for spring operations this year appear widespread, stretching across the south and southeast of the country.
Also, the sheer number of Special Forces positioned across the region suggests that those teams are playing a lead role.
More than a dozen U.S. Chinook helicopters left a Kandahar airfield around sunset on 10 March, carrying Special Forces teams toward the mountains of southern and southeastern Afghanistan. The next night, the deep thumping of the twin-rotor Chinooks filled the darkness for hours, along with the sound of Blackhawk and Apache helicopter escorts.
Little information is available from the U.S. military about Special Forces operations in Afghanistan. But one aspect of their work is well-known because of its effectiveness against the Taliban regime in October and November 2001.
Once on the ground, Special Forces soldiers can guide precision bombs of U.S. Air Force and Navy planes with a device that "paints" a laser signature on a target. That signature is used by laser-guided bombs to locate the target.
When a Special Forces team used the technique to support General Abdul Rashid Dostum in his battles against the Taliban in late 2001, Dostum reportedly used the Taliban's own radio frequencies to demoralize them -- telling them seconds ahead of an air strike that the Americans were about to use their "death ray."
At the Bagram airfield north of Kabul, more than a dozen U.S. Air Force A-10 Warthog attack planes and Navy fighter jets are lined up with laser-guided bombs to provide close air support to ground troops in the spring operations.
Officers in the U.S. Army who work beside the Special Forces teams spoke to RFE/RL in general about the ongoing operations.
Lieutenant Colonel Joe DiChairo commands about 1,000 soldiers of the Triple Deuce -- the nickname for the 2nd Battalion-22nd Infantry Regiment of the U.S. Army's 10th Mountain Division.
"There's no doubt that they are here and that they work throughout Afghanistan -- Special Forces. To the extent that we work with them, I can't comment on for operational reasons. I can tell you it's always smart business when forces work together. The more you can synchronize your efforts, the better," DiChairo said.
Most of DiChairo's troops are deployed in Kandahar Province. But one of the five companies in his battalion moved in January to a location near Qalat, the capital of neighboring Zabol Province. The regiment has set up a forward base there, which can be used to deploy combat teams and provide them with logistical support.
The compound is near a rugged mountain area between Taliban leader Mullah Omar's home province of Oruzgun and Pakistan's tribal region of South Waziristan, where Osama bin Laden once was thought to be sheltering.
Correspondents who visited the base before it was closed to journalists last week report that it, like other such bases in Afghanistan, is crowded with Special Forces soldiers.
DiChairo's unit is a team of combat troops who specialize in mountain warfare. They conduct security patrols to prevent Islamic militants from sneaking from the border areas near Pakistan into Afghanistan's interior.
"We've been given an area of operations that suits our force size in Qalat. And our goal in doing security operations is to disrupt any Taliban lines of communication that may exist. Lines of communication, in layman terms, are transit points or transient locations. [Our goal also is] to defeat [the Taliban] if [it] decides to confront us, which [it] has not done yet directly," DiChairo said.
DiChairo did not rule out the possibility that some of his troops may take part in sweeps of the region to flush out insurgents. He says that after eight months in Afghanistan, his soldiers are prepared for the full spectrum of high-altitude operations.
But DiChairo says the phrase "spring offensive" does not reflect his part of the mission. He said a better description would be "routine and deliberate operations." The phrase "deliberate operations" suggests that the regiment will be doing more security patrols for extended periods of time in some areas.
While officers like DiChairo are more open to questions from journalists than Special Forces troops themselves, some information does surface about the so-called Green Berets when they become engaged in combat.
Early on 10 March, provincial Afghan militia fighters in the eastern province of Nangarhar fired at American military vehicles that had approached their checkpoint with their lights off. One U.S. official told RFE/RL that the description of the convoy sounded like a Special Forces operation.
Dawlat Khan, a Nangarhar border security official, described the incident as a misunderstanding. He said the Afghans were border guards and had fired warning shots because they wanted to know who was approaching them in the darkness.
Khan said one Afghan was wounded when the U.S. soldiers returned fire. The other Afghans fled into the mountains. He said the Americans destroyed their abandoned weapons and arrested four Afghans during a search of a nearby village.
Last weekend, U.S. Special Forces shot dead nine suspected Taliban and Al-Qaeda fighters outside a base near the town of Orgun in Paktika Province.
The presence in Pakistan of a Special Forces team called Task Force 121 also has been widely reported in the Western press, despite President Pervez Musharraf's repeated denials of any American forces in Pakistan's tribal border areas.