Iran's unreasonable detention of British sailors and marines amid obstinacy about its nuclear programme is solidifying the country's international image as that of a pariah state. Only by proving otherwise - starting with the immediate and unconditional release of the captives - can Tehran hope for a fair hearing internationally on matters of diplomatic and strategic concern. The nation has no justification for holding the 14 men and one woman. Being on a United Nations-sanctioned mission to prevent smuggling to neighbouring Iraq when detained 10 days ago, the naval personnel were protected by international law. Whether their ship was in Iranian waters, as Tehran claims, is immaterial - the purpose of their work was clear. To claim otherwise is to ignore the authority of the UN. Nor is this incident markedly different from that in 2004, when Iran detained eight British sailors in the same area under similar circumstances. That time they were freed after several days; this time, the captives' human rights are being violated through their illegal detention and by being paraded before Iranian television cameras and apparently forced to make on-air and written confessions. The country has already contravened international rules by refusing to accept UN Security Council resolutions on transparency of its nuclear programme. Suspicion that Tehran is using the excuse of a need for atomic power as a cover to build nuclear weapons is hardened by this rejection. Limited sanctions have already been imposed by the Security Council over the nuclear programme and now by Britain as a result of the detentions. If Iran wants to avoid tougher measures, it must toe the international line. Iran is not being unfairly treated. There are rules which UN members have signed up to and its refusal to abide by them puts in jeopardy its right to enjoy the benefits of membership. Loss of those rights through the imposition of further sanctions would affect Iran's struggling economy. Isolation would only harm the nation, as has been proven time and again over the decades when such measures were imposed against governments; North Korea and Iraq are poignant examples. Iran's leaders would seem to have any number of reasons for their actions: Among them, to divert attention from the nuclear issue; to create leverage with the US over the arrest of five Iranians accused of terrorism in Iraq in January; to push for greater involvement in brokering peace in the region; a show of supremacy by the hardline leadership over moderate opponents; and a declaration by the nation of its global might. Iranians have a proud history stretching back millennia. That pride was clearly on show in 1979 when the US-backed shah was overthrown by Muslim hardliners and an Islamic nation created. It was central to the hostage-taking by students at the US embassy in Tehran, an incident that ended after 455 days. That hostage-taking damaged the leadership's international standing and it is again being harmed. There is nothing positive to be gained from such an approach. Iran has numerous issues of concern, but shows of force are no way of dealing with them. Ignoring international laws and rejecting the accepted manner of mediation - diplomacy - is a sure-fire way to lose support. The Britons must be freed - and only then can the proper, diplomatic, channels for discussion be opened.