On our way into Kosovo we stopped to look up into the bright morning sky where a NATO jet, small as a gnat, roared in from Albania before wheeling abruptly and racing away.
Thirty seconds later and at least 10 kilometres away at the base of a mountain, two huge brown mushroom clouds shot into the air, followed moments later by the noise of the detonations, thunder claps even at this range.
Crossing the border is an anticlimax. You walk down a dirt road, cross a broken wire fence and you are inside Kosovo. There are no markers and the landscape is the same - thick woods, rolling hills and grassy meadows covered in heather and a blaze of bright yellow flowers. The only difference is the mines.
Our guide, a Kosovo Liberation Army military policeman wearing a mixture of American and German battle fatigues, warns us to keep to the path as we walk into the enclave 10 km wide by five km deep, which the KLA has gouged into Serb lines.
We pass stores of KLA ammunition, hundreds of mortar bombs still in their wooden crates stacked under trees, a sign of the supplies now reaching the KLA.
On either side of the path are clusters of brown craters from Serb mortar bombs and the corpse of a cow chopped in half by one blast and left to rot. Pointing at it our guide says: "If you are scared you get hit - that cow was scared."
The only sound apart from bird song on this perfect spring day is the lazy drone of the propeller of an unmanned US reconnaissance aircraft overhead.
It flies backwards and forwards endlessly over the front line, its TV camera watching the Serb lines like a hawk, ready to summon NATO jets should a Serb tank, truck or even soldier dare to break cover. None did, and we walked on, descending down a steep earth path, gratefully into the cool of thick trees.
It has taken seven weeks for the KLA, fighting often hand-to-hand, to push the Serbs back through this riot of greenery and deep ravines.
Then through the trees we see the rebel base, a red-brick former border post of the Serbs, the holes in the brickwork showing where the KLA bazooka rounds impacted when it was seized last month. An Albanian flag, black eagles on a red background, fluttered outside.
The KLA unit on Koshare Mountain has two objectives. First moving down from the top slopes, capturing the foothills and breaking through to other KLA units which are now trapped on the plain of Djakovica, which we can see spread out before us. Already, claims the KLA, NATO strikes have smashed most of the Serb artillery positions and have reduced Serb forces to keeping open only corridors through the province along the main roads, with the KLA free to roam the countryside. But the rebels are hamstrung by lack of ammunition. "We don't have much ammunition, it is difficult to smuggle it in," I was told two nights before when I bumped into a rebel soldier I met last year in Kosovo when he was holding down a normal job. "Once we make a link with the guys in Koshare - bingo!" he said, using a KLA phrase which describes success or a lucky hit.
In almost two months of fighting, KLA commanders believe that the tables are slowly, grindingly turning in their favour. Now it is the KLA which has plenty of men while the Serbs, bombed by NATO, are running short of supplies.
The second objective - more difficult, more problematic - is to find a way of pushing troops down the side of Koshare Mountain, parallel to the border, and up the far slope. This would open the way leading from Djakovica across the border to the Albanian town of Bajram Curri, allowing the rebels, and perhaps NATO too, to drive in supplies.
Inside the Koshare base a senior officer with the 138 brigade Esat Krasniqi, said: "We have done our mistakes, we have gained experience in one and a half years. Now we are training to fight in the NATO way, fast actions, small groups."
Maps, charts and esoteric artillery firing diagrams cover his desk. On the wall, by the red fire bell, are two wooden framed pictures left by the Serbs. One is inscribed Catherine Zeta Jones, and shows plunging cleavage and fishnet stockings. The other is a tapestry entirely made in camouflage uniform colours, and shows a girl more modestly attired with a bright dress and flowers under her arm. A message comes over the radio, an intercept of the co-ordinates given by a Serb commander to his artillery. They are for this building.
Commander Krasniqi, a brother of the KLA's press officer, excuses himself, shuts the door and barks orders to soldiers in the corridor to move downstairs, under concrete, leaving me and my translator staring out of the window. A shell thumps outside and then another. Commander Krasniqi returns, and asks us to come to lunch.
We sit, unhappily sipping vegetable soup and nibbling at hunks of bread and pickled beetroot as the explosions march around the building.
At each detonation, the windows rattle but the soldiers tucking in around us are unfazed. "This happens a lot," says Commander Krasniqi. "But it is hard for them to get the angle to hit the house. Anyway, they are after our artillery in the hills. They don't hit this building - well, only occasionally." He looks at me. "You need more coffee," he says.
An almighty crash sounds outside. Everything shakes, the coffee in my cup ripples, and I think about the holes I have seen in the roof of this building made by previous Serb "bingos".
In the end we are moved downstairs where a nervous Italian journalist is already waiting along with some troops in the gloom. There are more detonations, incredible crashes, much louder than anything television manages to convey.
Some reporters live for these moments, relishing the action. Not me. I make a mental note never to brag about being in the thick of it. Instead, if I get out of here, I will remember this fear that seems to creep around inside your body.
Commander Krasniqi is back once more. "Time to go," he beams. I had planned on staying, at least until the end of the bombardment. His soldiers exchange smiles as he points to the bright square of light which forms the doorway and which I expect at any moment to shatter into fiery chaos.
"Don't forget to pick up your press pass on the way out," he said. I thank him for lunch.
Outside we stumble up the hill, the spectacular view of Kosovo now looking threatening - all those Serb eyes. But there is still time to notice that most of the houses spread out down there still have their red roofs, showing that some parts of the province have escaped the burning inflicted by the Serb paramilitaries.
We walk, agonisingly slowly, back up the hill towards Albania, while Serb shells hammer over a tree ridge behind us. Finally, we stumble back over the border fence, where I can't help but noticing a giant shell crater that wasn't there that morning.
A distant bump and my translator says we have about 20 seconds before a shell we just heard being fired comes into land. I wait. After 20 seconds I am about to tell him he is wrong when an ear-splitting roar sounds someway behind us.
It's no good, I jump with fright while our escorting soldiers roar with laughter.
Later, camped at a KLA special forces base, we sit around a fire made from the ruins of a fence. A fierce artillery duel develops. The KLA soldiers, as if to demonstrate their abundance of supplies, are banging away with mortars nearby. The Serbs are also using mortars but in groups, causing the shells to land together in rippling explosions.
Night falls and the mountain goes silent. A doctor arrives, the burning embers reflecting in his glasses.
He says that day's shelling has cost the KLA three wounded and no dead. He was called to a Serb position, newly overrun, where two Serbian soldiers lay badly wounded.
One had held a grenade to his stomach threatening to pull the pin if the Albanians approached. So instead, the doctor had stayed back, and waited, and before midnight both injured men had bled to death.