NATO officials say the Taliban has concentrated forces in at least five southern and western provinces of Afghanistan -- Helmand, Kandahar, Farah, Uruzgan, and Ghor.
"What the Taliban is trying to achieve by this series of attacks -- as widespread as possible -- is to divert NATO efforts across the country."
NATO spokesman Colonel Tom Collins says militants in those areas are preparing to carry out attacks in those provinces as part of an "expected spring offensive."
Offensive Under Way?
But Taliban commanders say they began their spring offensive on February 2 when militants seized the town of Musa Qala in Helmand Province.
Militants continue to control Musa Qala, which is about 25 kilometers from a key reconstruction project in southern Afghanistan, the Kajaki hydroelectric dam.
Meanwhile, correspondents at Kajaki report that several hundred British Royal Marines have been fighting on a daily basis to keep the Taliban far enough from the dam so that reconstruction work can continue.
Security analysts say operations near the dam are likely to be the major focus of fighting throughout the spring.
Meanwhile, in the western Farah Province, several hundred Taliban fighters seized the remote district of Bakwa on February 19. It was the second time this month that the Afghan government has lost control of a district.
Within 24 hours, however, the Taliban vacated Bakwa, the district's administrative center. That allowed 200 Afghan troops to be deployed in the town unopposed the next day. But scores of Taliban fighters are thought to have spread out across the remote district.
Pakistani journalist Ahmed Rashid, an expert on Islamic militants and author of the book "Taliban," tells RFE/RL that simultaneous mass attacks by the Taliban could pose a serious threat to NATO forces in the months ahead.
"The Taliban last year fought positional warfare, trying to hold ground and hold territory in three provinces: Oruzgan, Helmand, and Kandahar," he said. "The danger this year is that they may try and launch heavy guerrilla attacks -- with perhaps 200 men at a time -- not just in three provinces but perhaps in six or seven provinces. Even in western Afghanistan. If they do that, NATO is going to be very stretched. That restricts NATO's ability to counter a widespread Taliban offensive."
As fighting raged in the provinces of Helmand and Farah this week, the Taliban simultaneously launched a series of smaller attacks in other parts of the country.
On February 19, in the eastern Kunar Province, U.S. troops engaged Taliban fighters near the border with Pakistan in a clash that killed one U.S. soldier.
Using Guerrilla Tactics
Also on February 19, militants in the southern part of Oruzgan Province ambushed Afghan and NATO forces as they tried to dismantle a roadside bomb.
Then, on February 20, a Taliban suicide bomber disguised as a doctor injured seven U.S. soldiers when he blew himself up at a hospital in the southeastern Khost Province.
Ian Kemp, an independent London-based defense analyst, says the Taliban's guerrilla tactics can give them an advantage when they carry out small isolated attacks.
"The insurgents in Afghanistan, they are able to pick the time and place of their attacks," Kemp said. "And that is always going to give them an advantage. The NATO forces are going to be dispersed throughout the country. And they are going to be hard pushed to protect a number of high priority installations."
Kemp says the main goal of the Taliban offensive is to undermine the confidence of ordinary Afghans in NATO-led and Afghan government security forces.
Thousands Of Insurgents
"What the Taliban is trying to achieve by this series of attacks -- as widespread as possible -- is to divert NATO efforts across the country," he said. "The Taliban knows that NATO cannot spread its troops throughout the country. And they are hoping to undermine confidence among the Afghan population -- both in NATO and in the ability of the Afghan security forces -- the police and the Afghan National Army."
But Kemp say Taliban fighters make a fatal error when they mass together in large numbers to hold a town or strategic territory.
"Often the pattern we see is that the Taliban launch an attack and then are able to say that they've retaken a town," he said. "But often the Taliban then fade away within a day or two before NATO has had an opportunity to counterattack. The NATO commanders on the ground actually prefer it if the Taliban take a village and stand and fight -- because NATO is able to deploy air power, to deploy artillery. It's able to deploy well-trained infantry. Certainly, what is more difficult, is when the Taliban stage an operation and then disperse."
Taliban commander Mullah Dadullah told Al-Jazeera television on February 22 that 6,000 Taliban fighters are now deployed across Afghanistan and are ready to carry out more guerrilla and suicide attacks.
Last year, Taliban-led militants carried out about 140 suicide attacks in a wave of violence that made 2006 the bloodiest year of fighting in Afghanistan since the ouster of the Taliban regime in 2001.