A Nato military source said pilot training was complete. The 22-strong unit would be battle-ready as soon as the White House authorised deployment.
Despite intense speculation, the helicopters, equipped with "Hellfire" anti-tank missiles, have so far been used only in training missions - resulting in two losses, including one fatal crash.
Yesterday's comments coincided with new claims of success against Serb forces, who suffered a barrage of attacks all day on Tuesday, according to Nato sources.
The alliance said it had struck tanks, armoured vehicles, artillery positions and command posts.
Nato's Supreme Allied Commander in Europe, General Wesley Clark, finished his morning call to fellow generals yesterday with the words: "This is the best day of work of the air campaign so far."
However, 50 days into an air campaign which was supposed to teach President Slobodan Milosevic of Yugoslavia a short, sharp lesson, General Clark's observation says more about the alliance's slow progress than its military results. In truth, Nato is reluctant to say how much military hardware it has destroyed. Nor will it predict how long Serb armed units can carry on in Kosovo.
In part, this derives from caution borne out of the Gulf War, when the military tended to overestimate achievements.
Nato officials agree that the hit-rate of its air raids is improving, but only from a low base. And the emphasis of the accounts given in daily briefings differs, depending on whether Nato is seeking to highlight its military successes or the continuing brutality of Serb ethnic cleansing.
One senior source argues that the air campaign has "settled down" after a disastrous start: "At the beginning, the military were coming in saying, `Last night we flew 12 sorties; 11 were abandoned because of the weather, and we're not sure if the other one hit anything.' That has changed."
Nato has been aided by the improving weather, greater experience in flying missions and re-inforcements which have allowed the allies to fly around the clock when conditions permit. More missions are being flown at lower altitudes.
But the alliance remains opaque about the actual destruction inflicted on Yugoslavia's military machine. The latest assessment of damage to forces in Kosovo said the alliance had hit - rather than destroyed - one in five Serb tanks and pieces of heavy armour.
That was well on the way to a target of 50 per cent destruction, Nato argued. "At that stage, the forces concerned focus on survival rather than fighting," said General Walter Jertz, Nato's military spokesman. "Milosevic's forces are being taken apart, bit by bit, faster and faster."
Yesterday, the general qualified his statement, saying that his 50 per cent figure was one based on military practice in the West, and that Mr Milosevic's forces might be made to fight on with, perhaps, 30 per cent of their heavy equipment intact.
Even more doubt surrounds Nato claims that Yugoslavian forces are isolated and suffering from dwindling supplies and low morale. Nato denies that it is heading for a military stalemate with Belgrade. Having cut off supply routes, it says the Serbs' ability to survive is limited. Yet the level of morale among the Serb military and paramilitary forces is unclear, and they appear to have prepared for a long campaign.
One senior Nato source said the Yugoslavian army was good at improvising - cannibalising old vehicles for spare parts and foraging for food from the countryside.