IRA reported to get huge arms shipment from Libya. But terrorism experts are at a loss to explain the massive deliveries

What is the outlawed Provisional Irish Republican Army planning to do with more than 3,000 AK-47 assault rifles, as well as howitzer artillery and SAM-7 missiles from Libya? Terrorism analysts in Washington, London, and Dublin are pondering this, as 7,000 British and Irish troops and police comb the Irish countryside for the hidden arms.

The ongoing investigation comes on the heels of a Chicago jury's conviction of five members of a street gang for conspiring to carry out terrorist acts on behalf of Libya. These events point to Libya's strong and continued support of terrorism, United States specialists say.

Details of the reported massive weapons shipments have emerged following France's Oct. 30 interception of a 150- to 200-ton arms shipment from Libya. French, British, and American intelligence sources confirm that the arms were destined for the IRA, which is fighting to end British rule in the province of Northern Ireland. They now say that this is only one of five shipments from Libya to the Irish rebels - two were delivered in 1985 and two in 1986.

The Irish arms totals, which news reports say could amount to 300 to 400 tons of weapons and ammunition, have stunned terrorism experts. They go far beyond what the IRA has used in the past and what it is believed capable of using today.

For example, experts say the IRA fighters only number in the hundreds and thus ask why they would need 3,000 rifles or why the IRA would want the howitzer artillery that was reportedly sent.

The consensus is that the Soviet-made antiaircraft SAM-7 missiles, which can be carried and fired by one man, were sought to hit British troop helicopters, used for rapid mobility in Northern Ireland, where most of the combat in the 18-year conflict takes place. An Irish expert on the IRA says that IRA leaders sought a shoulder-fired missile in hope of dramatically changing the battlefield situation, as have Afghan and Angola rebels seeking US-made Stinger missiles.

Some Irish and British police have speculated that the IRA planned to assault prisons in Northern Ireland and the Irish Republic, where hundreds of IRA activists are imprisoned. But, as the multi-nation investigation reveals the immensity of earlier arms deliveries, officials are puzzled.

Officials in Washington, Dublin, and Paris, offer three theories to explain the arms shipments:

Transit point. The arms were destined only in part for the IRA and some were to be used elsewhere later on. In addition, terrorism experts say the IRA could have agreed to carry out attacks for the Libyans in exchange for the arms. European intelligence sources say Libya has hired mercenaries in recent months to strike in Europe.

Insurrection. The arms could have been acquired for use in an eventual insurrection in the North or the Republic. Though such a move would seem suicidal and detrimental to public support in the South, the size of the arms deliveries makes such a mission possible.

No plan. The IRA had been in need of weapons for so long that once it found a willing source it bought too many. One Irish specialist says the IRA has not received large arms resupply since the early 1970s and has been using home-made mortars, for example. It may simply have asked for much more than it can now use, speculates a British official.

The arms revelations come at a bad time for the IRA. The Nov. 8 IRA bombing in Enniskillen, Northern Ireland, which killed 11 and wounded 63 civilians, created a massive backlash in the Irish Republic as well as in the North, say a senior Western diplomat in Dublin and the expert on the IRA.

The bombing seems to have dashed IRA hopes that Ireland would not adhere to the European Convention on Terrorism this year, these sources say. The convention would require Ireland to extradite alleged terrorists wanted for specific crimes, including murder, even if they claim a political motivation for the crime.

They add that political support for the IRA has been declining. Sinn Fein, the political arm of the IRA, received only 1.9 percent of the vote in this year's parliamentary elections in the Irish Republic and its vote total dropped 25 percent in the last vote in the North.

British and American officials were effusive in their praise for France's role in intercepting the shipment.

The Nov. 24 conviction of five members of the Moslem ``El Rukn'' gang in Chicago reveals a pattern evident in other countries, he says. A radical group seeks out the Libyans for funding and the Libyans agree, often seeking terrorist actions in return. The El Rukn members were convicted of conspiring to blow up airplanes and US government buildings in return for up to $2.5 million from Libya.