The Central Intelligence Agency has spent $3 billion on arms for Afghan rebels -- half of it put up by U.S. taxpayers. Yet not a single American decides who gets the weapons.

The CIA leaves those decisions to a secret five-member directorate of top Pakistani officials, who have their own agenda. This means the CIA's largest covert aid program since Vietnam has made rich sugar daddies out of Pakistani generals.

From our investigation, which included a trip by Dale Van Atta to Pakistan, we have found that the CIA's secret arms pipeline to the mujaheddin is riddled with opportunities for corruption. The losers are the poorly equipped guerrillas fighting the Soviets in Afghanistan and the American people whose congressional representatives have been betrayed by the CIA.

Here's how the Pakistani portion of the pipeline works:

The CIA purchases Soviet-designed weapons primarily from Egypt and the People's Republic of China. Some Chinese weapons are shipped in convoys along Karakoram Highway, a rugged road cut through high mountains into Pakistan. But most come to the country's southern port, Karachi.

There customs agents look the other way as the shipments -- labeled as food, engineering parts and such -- are loaded on trucks and trains headed to distribution warehouses in Peshawar and Quetta.

The CIA's orders are unequivocal: No CIA official is to have direct contact with the mujaheddin, except to train them on U.S. Stinger antiaircraft missiles. Because the Pakistanis risk retaliation from the Soviet Union, the CIA lets them decide which competing rebel factions get what weapons.

For several years, those decisions were made by a five-member committee including Maj. Gen. Akhtar Abdul Rahman, head of military intelligence; Gen. Rahimuddin, chairman of the Pakistani joint chiefs of staff; Gen. Fazal Haq, the former governor of Peshawar, and Foreign Minister Yaqub Khan. (Haq and Rahimuddin recently retired; Rahman was recently made vice chief of the Army staff.)

Once the arms are assigned, 200 troops and 11 officers under the orders of Brig. Gens. Reza and Youssef distribute them. Youssef, who has a reputation for integrity, has attempted not only to give the most deserving rebel groups the right arms but to help the mujaheddin plan battles. But he is an exception.

Intelligence sources (including CIA officials) and Pakistani sources charge that some Pakistani soldiers have become rich in the process.

Another intelligence source, however, maintains that the Pakistanis "are good soldiers, and they want to help . . . . They really want to win this war."

The Pakistani generals also transfer intelligence packets the CIA gathers for the mujaheddin. The mujaheddin have privately complained that the packets are usually opened by Pakistani officials before they receive them -- which suggests information may be compromised.

Still, one source intimate with the entire operation concluded -- as we have in previous columns -- that "the opportunities for diversion and corruption are far greater before the arms get to Karachi than after."