A message delivered in Tripoli but aimed at Baghdad and Washington

For all the excitement being drummed up by the Foreign Office, this week's visit to Libya by a Foreign Office minister is hardly to be equated with Richard Nixon's epoch-making trip to China. Britain resumed full diplomatic relations with Libya three years ago. Even if Mike O'Brien is the first official of his rank to set foot in Libya for 20 years, his visit to Tripoli is all in the predictable order of slowly improving bilateral relations.

Yet there is more to Mr O'Brien's three-day visit than meets the eye. Although expectations of a meeting with Colonel Gaddafi were played down by both sides, it is hardly likely that the Foreign Office would have made such great play of Mr O'Brien's impending departure, to the point of encouraging journalists to accompany him, unless the Libyans had virtually guaranteed such a meeting in advance. Mr O'Brien duly left Tripoli yesterday morning for the coastal city of Sirte, and the promised encounter.

Such a meeting is well beyond the requirements of protocol and implies a measure of goodwill towards Britain on the Libyan side that has been little in evidence for many a year. The shooting of WPC Yvonne Fletcher by a Libyan embassy official in 1984 prompted diplomatic relations to be summarily severed and poisons relations to this day. Four years later, the investigation into the Lockerbie air crash only confirmed Libya as a villain of the first order and established Colonel Gaddafi as an international pariah. Libya was also aiding the IRA and other international terrorist organisations.

It has taken almost a generation since the death of WPC Fletcher for relations to thaw even to their present tepid state. The breakthrough – and the cue for the UN to lift sanctions and for Britain, among others, to resume diplomatic relations – came in 1999, when Libya agreed to surrender the two Lockerbie suspects to Scottish jurisdiction. The trial that followed, with its Solomon-like judgment in which one defendant was convicted and one acquitted, passed without notable histrionics from Tripoli. After 11 September, Libya again surprised the Western world by sending condolences to the US on the terrorist attacks. In June, Libya marked a realignment of its policies away from the Middle East and towards Africa with a sizeable presence at the African summit in Durban.

Mr O'Brien's meetings in Libya are a manifestation of all these changes, but an exploratory mission also: to find out how far Mr Gaddafi's attitudes have changed, and in particular whether he has abandoned his one-time support for international terrorism. What is needed is for Libya to give a solemn commitment to dissociate itself from terrorism, to sign up to those international weapons treaties it has so far kept at arm's length, and to pay the court-ordered compensation to the families of the Lockerbie bombing.

It is clear that Mr O'Brien's trip is of much more than bilateral significance. Speaking yesterday, the minister said that the US administration knew of, and supported, it. Mr O'Brien is therefore representing the West as well as Britain. But he also stressed that Libya was more likely to move away from international terrorism "if it is part of the international community". This is a message that is intended to be heard not just in Tripoli, but in Baghdad and Washington as well. If Libya can rehabilitate itself to become a fully paid-up member of the civilised world, then so can Iraq. Time, persuasion and step-by-step engagement are more effective means of changing behaviour than bombs.