International Effort Limits Scope of IRA Violence

A CONCERTED international effort involving the Irish Republic, the European continent, and North America is paying dividends in Britain's battle to defeat the IRA. One month before the 20th anniversary of the deployment of British troops in Northern Ireland, authorities in London and Belfast are claiming that the new transnational approach is turning what the outlawed Irish Republican Army (IRA) said would be a summer of terror into a relatively calm season.

The successes notched up in the past month include:

The arrest in France of three people believed to have been involved in a series of IRA bomb attacks on British Army units in West Germany.

The detention a week earlier by police in the Irish Republic of two other people thought to have helped plan bombing operations in Europe.

The uncovering in Boston of an alleged attempt by American radar experts to help the IRA obtain missile-guidance systems for use against British forces in Ulster.

Security sources say there is much closer liaison between the Royal Ulster Constabulary, Northern Ireland's police force, and the Irish Garda south of the border.

It has taken a long time to build up the present level of trust. The starting point was the November 1985 Anglo-Irish Agreement. Now there is continuous consultation and a coordinated (though ultra-secret) system of cross-border security. Antiterrorist agreements reached privately between Prime Minister Margaret Thatcher and other European leaders, including France's President Fran,cois Mitterrand and West German Chancellor Helmut Kohl, has also contributed to closer cooperation.

The past month's record shows the dividends of cooperation: In early July, two people traveling via sea ferry from France were arrested when they arrived in the Irish Republic. They were found to be carrying explosive devices and documents giving details of military establishments in West Germany.

This gave police leads on a July 2 bomb attack near Hanover, West Germany, that killed a British serviceman and injured his four young children. Other documents led French police to Saint Avold where three suspects were arrested July 14.

On the other side of the Atlantic, cooperation between Scotland Yard and the US Federal Bureau of Investigation led to the July 14 arrest of two US citizens. They are accused of offering the IRA information on the building of electronically guided weapons.

It is too early to say whether the tide is finally turning against the IRA, two decades after Britain decided to intervene directly with troops in Ulster. Supplies of explosives and weapons believed to have come from Libya are still available to the IRA. Security sources in London and Belfast say the IRA is split between a moderate wing, which sees increased violence as counterproductive, and a militant wing, which believes it must internationalize its operations.