American soldiers in the mountain valley of Deh Chopan expect to be targeted by an unseen enemy. But the amateurish hit-and-run attacks of the Taliban - wildly fired rockets and mistimed roadside bombs - rarely inflict casualties. It was a shock, then, when a patrol was ambushed a fortnight ago with rocket-propelled grenades and sustained small arms fire. Six Americans were wounded. Two had their legs blown off. Two more were wounded badly enough to require evacuation to Germany for surgery.
The outcome of the ferocious five-hour battle was predictable enough - withering air power obliterated the Americans' enemies - but not before a US unit had suffered serious casualties and was forced to fall back before a determined enemy assault. A couple of days later nine Afghan National Army (ANA) soldiers died when they were ambushed by machine-gun fire as they got down from a truck in Kandahar province - the newly formed ANA's worst-ever combat loss. Then two US marines were killed in a cave where they had insurgents pinned down.
This wasn't what US military planners were expecting at the start of this spring's "fighting season" when the snow thaws in the mountains. After all, Afghanistan is supposed to be the war that the American military has won. The official emphasis has changed from combat operations to "hearts and minds" programmes.
Then, over the freezing Afghan winter, there were few attacks, leading to talk from the Kabul government and US military that the Taliban were short of recruits and low on morale. Soon, went the word, their commanders would be joining the amnesty set up to lure tired fighters in from the mountains. This programme is the hoped-for endgame after three and a half years of desultory guerrilla warfare which has tied down 18,000 US combat troops and cost the Pentagon more than $10bn (£5.4bn) a year. The military is desperate to scale down troop numbers after September's parliamentary elections and hand over to Afghan forces and the 5,000 British troops who arrive at the end of this year.
That plan may now need a rethink. Instead of fizzling out, the Taliban have staged what has become a now-annual spring resurgence, and with a surprising new fighting spirit. Particularly worrying are signs that al-Qa'ida may once again be taking an interest in the war in Afghanistan. Since their rout in 2001 and the fall of their Taliban allies, the Arab and Chechen fighters loyal to Osama bin Laden seem to have concentrated efforts on Iraq, or simply on survival in the tribal belt of Pakistan. Now there are fears that surviving elements may be trying to open a second front to Iraq. Fighting spirit has been rare among the Afghan recruits from the religious schools, the boys the Taliban fling into battle usually to be slaughtered. But this year their ranks seem to have been reinforced by more experienced and more determined men.
The soldiers at Deh Chopan found evidence of that. When they had finished combing through the body parts of their enemies, among the 44 dead were Chechens and Pakistanis, feared al-Qa'ida fighters. Other reports indicate that more sophisticated tactics are being used and that new weapons are being smuggled in over the Pakistan border. When a Romanian soldier was killed near Kandahar last month it was a modern anti-tank mine that blew up his armoured personnel carrier, not an improvised bomb or one of the old Soviet landmines that frequently don't work.
Further north along the Pakistan border, near Khost, the war hasbecome a hot one - human waves of Taliban fighters launch night assaults against the fortified bases of an Afghan mercenary force recruited by the CIA. Those insurgents are under the command of an old warlord with links to Saudi Arabia - Jalaluddin Haqqani - whose Pakistan-based operations seem to have received a new infusion of Gulf money.
The capital, Kabul, has also seen a revival in terrorism. An apparent suicide bomb attack on a Kabul internet café popular with foreigners killed a UN employee and terrified foreign aid workers and diplomats. Then the worst anti-US riots since the fall of the Taliban devastated eastern Afghanistan last week. Seven died, aid agency buildings were burnt and looted, causing millions of dollars of damage.
Orchestrated as they may have been, the riots showed a new mood of anti-Americanism which will worry the US military and the Kabul government. The flashpoint for the protests were claims that the Koran had been desecrated during an interrogation at Guantanamo Bay, but the agitators found a willing following among Afghans angry with America. US commanders still insist they are winning in Afghanistan. In briefings they claim that Afghans who are sick of the war increasingly come forward with information about insurgent activity.
The tone has changed in recent months, however, with the outgoing US commander, General David Barno, warning of the danger of "terrorist spectaculars" and of a hard core of Taliban who would not surrender but fight on as a "wholly owned al-Qa'ida subsidiary".
The US military machine cannot really be damaged by a low-level insurgency that refuses to die, and US forces suffer nothing like the terrible casualty figures in Iraq. But increasingly it looks less and less as if the US military has won and more and more as if GIs are bogged down in a guerrilla war that threatens to go on for years to come.
INTERNET-HAGANAH.US: "TALIBAN ONLINE UPDATE http://www.taliban-online.info/ loads content from http://tonline.dkmhosting.com/mpn/index.php" (ARTICLE SNIPPET: "Finally, there's a Taliban Online eGroup, but it doesn't look particularly active: http://groups.yahoo.com/group/taliban_online/") (April 22, 2005)