David Owen: What makes a dictator pack his bags?

We all want to see Gaddafi and Assad face their just deserts, but politicians have to reconcile justice with pragmatism

When the Arab Spring started in Tunisia last December and quickly spread to Egypt, it was predictable that the greatest political and military challenge for Europe would come from Libya. Colonel Gaddafi's long record of support for terrorism and brutality against his own people had, for six years, been masked by an apparent readiness to abandon both terrorism and a nuclear weapons programme. But by March 2011, the grotesque language of Gaddafi's son Saif threatening to destroy Benghazi, Libya's second largest city, confirmed the regime had no intention of changing.

Following a specific Arab League request, and French and British resolve, a no-fly zone over Libya was authorised by the Security Council. It is of long-term importance that China and Russia did not block the resolution and that the US wanted to be supportive but not take a lead role.

The German government and other EU dissenters from military action against Libya, should answer this: if we had let Gaddafi and his sons take Benghazi, what would have happened in Syria? Would the Syrian people still be fighting President Bashar Assad and his brother? Would Turkey be contemplating taking action against Assad? By a cruel coincidence of timing, just when the patience of the Turkish government was running out with the Assads, the upheaval in the Turkish military has been a huge distraction. Yet Turkey is the one country in the region capable of acting to stop the present Syrian slaughter. Israel wisely stays out of the conflict. The US rightly fears being blamed for exacerbating present tensions in Lebanon and provoking Hezbollah. Nevertheless, President Obama's decision last week to freeze Syrian assets and ban petroleum products is an important new pressure on Assad.

Overall, the implementation by Nato of the Libya no-fly zone has been a success, helping the liberation forces in the last few days to virtually control Zawiya close to Tripoli. But the price of UN-authorised intervention has been a strictly controlled and limited military operation and political intervention designed to necessitate negotiations between the Libyans.

This new form of constrained interventionism has been the inevitable consequence of US and UK failure in Iraq. It is something that China and Russia is likely in future to insist on to guide the "responsibility to protect" interpretation of the UN Charter agreed by the heads of government summit of 2005. Experience has also taught that forcefully removing despotic leaders is fraught with difficulty. The world has, however, designed a new legal mechanism for intervention. During the war in Bosnia, Cyrus Vance and I recommended that the Security Council should establish the International Criminal Tribunal for the former Yugoslavia (ICTY). President Milosevic was tried by this tribunal, but died or committed suicide before sentencing.

Tragically, the ICTY, established in 1993, did not prevent the genocide in Srebrenica in 1995. The big legal breakthrough came with the decision to bypass Security Council vetoes with a multinational treaty to establish an International Criminal Court (ICC). This Rome Statute came into force on 1 July 2002, and 116 states are ICC members. A further 34 countries, including Russia, have signed but not ratified. Israel and Sudan unsigned, as did the US under George W Bush, though the Obama administration is working with the court. China and India have neither signed nor ratified.

The ICC remains controversial. President al-Bashir of Sudan has already been indicted, but the African Union (AU) does not believe he should be sent to trial for crimes committed in Darfur and instead should be allowed to get on with the difficult task of dividing Sudan, as agreed in the recent referendum. There is also criticism within the AU that the indictment of Gaddafi makes it harder to persuade him to leave the country.

In Africa, it is widely believed that the readiness of Saudi Arabia to take President Idi Amin of Uganda in 1979 helped ease transition there. As Foreign Secretary, I was closely involved in aiding Tanzania to intervene militarily to oust Amin and have no doubt that he would have fought harder had he not been given sanctuary.

I do not believe, however, that Gaddafi has stayed in Libya just because of the ICC. This is a man of abnormal personality, whose conduct is totally unpredictable. If the Libyan negotiators representing all sections currently meeting in Tunisia decide to defy the ICC ruling and allow him to remain within their country and avoid trial – Libya is not a signatory to the statute creating the ICC – they can. That reality is not an ignominious defeat, as some claim. Until a successful negotiation is achieved among all Libyans, Nato must persist in helping the liberation forces fight the Gaddafi regime.

What happens in Tripoli always has a bearing on decision-making in Damascus. Is Gaddafi going to get away with it? There is a case for the Security Council referring the situation in Syria to the ICC. But, as in Libya, the endgame will likely be negotiations of enemies having to be reconciled. Negotiations are playing a role in Bahrain. In Iran, the only country likely to harbour the Assads, the unreconcilable among its leadership look for opportunities to exploit situations that will make the Arab Spring peter out. Iran has no interest in demonstrations for greater human rights succeeding – let alone bringing about a change of government in any Arab country which its leaders work with, particularly Syria.

This all combines to making it fundamental that Gaddafi loses power soon in Libya. The Bush-Blair days of unbridled intervention are over. Not only states but people demand respect for international law and proportionate use of military might. As Libya has shown, such constrained intervention takes patience and necessitates new mechanisms.

First and foremost, we need to see the establishment of an effective UN Rapid Reaction Force. It should be made up predominantly of forces provided by Security Council members, be well equipped and well trained. Britain and France should give the lead and commit jointly to providing from one or other's navy an aircraft carrier, if appropriate, to support the Rapid Reaction Force. The UK senior military, too cautious for action, got Libya wrong, as it got Afghanistan wrong by being too gung-ho about defeating the Taliban. Constrained intervention is the future global role for Britain's armed services.

Eventually the ICC statutes should be renegotiated to win the full-hearted support of the US, Russia, China and India, maybe bringing the court within the auspices of the UN, with some arrangement to overcome the fear of the veto power in the Security Council. And it must be given the flexibility required to judge between the sometimes conflicting priority of reconciliation or absolute justice.

David Owen was Foreign Secretary from 1977-1979