Whatever justification Taoiseach Bertie Ahern had for proposing Irish membership of NATO's "Partnership for Peace" last January has vanished in face of the war in Yugoslavia.

The political context of the debate on PfP changed fundamentally in March when NATO, which had been a Cold War defensive alliance and whose charter commits its members not to take up arms unless themselves attacked, went to war for the first time in its 50-year history. The circumstances are generally regarded as breaching international law.

International law may be a frail force in human affairs, but it is the only thing humanity has developed as a rule to govern relations between states. NATO has breached a whole slew of international laws by its actions in the Balkans.

Article 29 of the Constitution binds the State to accepting "the generally recognised principles of international law as its rule of conduct in its relations with other states". It commits the State to "the principle of the pacific settlement of international disputes by international arbitration or judicial interpretation".

How is that consistent with the statement of the EU states, including Ireland, in Berlin that NATO's bombing was "necessary and warranted"? Or with Ireland's linking itself to NATO through PfP, when that alliance has proved itself a partnership for war and has marginalised the UN?

Is it not obvious now that everyone would have been better off - not least the unfortunate Kosovo Albanian refugees - if NATO's bombing had never started and things could be brought back to where they were before March 24th? Talks over Kosovo could have continued; just as they will have to be renewed when the bombing stops. There is always room for further negotiation.

Unlike Iraq vis-a-vis Kuwait, Yugoslavia did not break international law by invading a neighbouring state. Instead, NATO violated the UN charter by assaulting a sovereign state without UN mandate. By bombing Yugoslavia, NATO is breaching the Geneva Convention, which makes it illegal in international law to go to war without an official declaration.

NATO's justification was that Yugoslavia/Serbia would not sign the Rambouillet accord, whereas the Kosovo Albanians did. Yet it violates the Vienna Convention on the Law of Treaties to seek to force one side to sign a treaty by threatening it with war; and there was no agreement at Rambouillet.

Many authorities hold that these recent breaches of international law by NATO only compound the breaches of 1992, when the US and the European Union - the latter urged by Germany - insisted on recognising the successor states of Tito's Yugoslavia within their existing, internal-Yugoslav, administrative boundaries. This violates the international law principles on recognising new states.

One wonders whether the other European neutrals, Sweden, Austria, Switzerland and the like, would have signed PfP agreements with NATO in recent years if they had foreseen these developments. In an interview on April 30th, President Milosevic said Ireland, as a neutral state, would be acceptable as part of a UN mission in Kosovo. Would Ireland be so acceptable if we were a PfP "partner" with NATO, one of the participants at that 50th anniversary weekend party which turned into a war conclave in Washington a fortnight ago?

PfP would commit the State to "the development of co-operative military relations with NATO, for the purpose of joint planning, training, and exercises" for various purposes. One of PfP's objectives is "the development, over the longer term, of forces that are better able to operate with those of the members of the Atlantic Alliance".

A NATO communique on PfP says: "Active participation in PfP will play an important role in the evolutionary process of the enlargement of NATO." The PfP Framework Document that Ireland would have to subscribe to includes the understanding that we would take part in NATO military exercises. As a PfP member, Ireland would have military staff at NATO headquarters. Our armed forces and equipment would have to adapt to NATO standards.

The whole enterprise, to put it crudely, can be expected to cost Irish taxpayers heavily if we embark on it. The huge investment agreed last year for 40 new armoured cars for the Defence Forces would be but a foretaste. No wonder those in the Army top brass are PfP enthusiasts. They have intervened in an unprecedented way in the political debate about it. That has rightly disturbed some. Is it a herald of the increased militarisation of Irish public discourse and foreign policy which signing a PfP agreement with NATO would almost certainly entail?

The proper role for the Army is to be available to support the civil power, and to serve in support of the UN in low weaponry-intensive Third World peacekeeping. There, Ireland has a special acceptability as a European state with an anti-imperial, anti-colonial past. Soldiering side by side with the former imperial powers under the umbrella of a NATO partnership is not a proper or honourable course for a country with Ireland's anti-imperial traditions.

There may be no constitutional necessity to hold a referendum before joining PfP, any more than there may be need for one to enable us become full NATO members. But a referendum on such a fundamental departure in Irish foreign and defence policy is surely necessary politically.

The Taoiseach himself made the best case for it while in opposition in 1996 when he said the case for joining PfP "has not been made". He went on: "We would regard any attempt to push Partnership for Peace or participation in Western European Union tasks by resolution through this House without reference to the people, who under our Constitution have the right `in final appeal to decide all questions of national policy', as a serious breach of faith and fundamentally undemocratic."

Fianna Fail said in its 1997 election manifesto: `We oppose Irish participation in NATO itself, in NATO-led organisations such as the Partnership for Peace, or in the WEU beyond observer status." But in recent weeks some party members have been courageous enough to say a referendum should be held.

The Labour Party has covered over its internal differences on PfP by uniting behind the call for a referendum. A wide range of distinguished public figures agree.

If NATO's going to war in breach of international law does not make Mr Ahern question the appropriateness of Ireland's linking itself to NATO through PfP, then a referendum is surely the way of political wisdom, prudence and democracy.

Anthony Coughlan is secretary of the National Platform organisation, which is opposed to Irish PfP membership.