Libya is a conundrum made in hell – or rather Downing Street

Nato and EU leaders huddling in Brussels, wondering what to do about Libya, face an uncomfortable emerging reality. Unless there is significant western military intervention to support the opposition and ensure Muammar Gaddafi's overthrow – and time is getting short – it seems increasingly likely he will survive the revolt. On current battlefield trends, Gaddafi is set to continue indefinitely as leader of western Libya and could eventually force all of the divided country back under his control. Then what will the west do?

The chief of US national intelligence, James Clapper, told Congress that Gaddafi was likely to prevail. This is not the scenario David Cameron envisaged when he prematurely declared Gaddafi was finished and should stand down. Perhaps the speed of the Tunisian and Egyptian revolutions, and the passivity with which Zine al-Abidine Ben Ali and Hosni Mubarak accepted their fate, encouraged false confidence in western capitals about the Libyan outcome. Whatever the reason, a sense of bluffs being called and petards being hoisted pervades the emergency Nato and EU deliberations.

When Downing Street first raised the idea of a no-fly zone and arming the rebels, the move appeared primarily designed to increase pressure on Gaddafi to go peacefully. When Barack Obama joined London and Paris in insisting the Libyan leader quit, it seemed the goal could be achieved without western countries firing a shot or, indeed, doing anything much at all. The rhetoric, both from the Libyan opposition and the west, was that this was Libya's revolution and Libyans alone would see it through to a successful conclusion.

Three weeks on, the case is very different. With Gaddafi's forces slowly gaining the upper hand, with dispirited and divided rebels calling desperately for foreign support, air cover and weapons, and with the Arab League and African Union apparently paralysed, it is increasingly clear that, if the revolution is to be salvaged, the west will have to jump in. Thus the result Cameron and others most wanted to avoid – the apparent co-opting of the Libyan revolt by western powers with all the negative implications that carries – moves dangerously close. They have, in effect, talked themselves into a position where logically they must act. Libya has become a giant strategic trap of their own making.

Reconnecting western policy to this unwelcome and unforeseen reality is taxing the best American strategic thinkers. According to Doyle McManus of the Los Angeles Times, "the debate over Libya this week in Washington isn't about what the US goal should be. Obama settled that question last week when he declared: 'It's time for Gaddafi to go'... Instead, the question is what role the US and its allies will play in the brutal and mercurial dictator's removal."

On this key issue, there is no agreement, with the White House, the state department, the Pentagon and Congress all offering differing and often contradictory opinions. Much the same Iraq-related disarray is evident in Britain, France, Germany and in Nato. To their ill-disguised horror, governments suddenly find themselves looking at high-risk, open-ended intervention in yet another Muslim country that is almost guaranteed, sooner or later, to enrage Islamic opinion.

Much criticism has been directed at Cameron's unwonted bullishness on Libya, rooted perhaps in his deep distaste for Tony Blair and Gordon Brown's perceived appeasement of Gaddafi. But Obama, too, is vulnerable to accusations of irresponsible grandstanding. During the Egyptian crisis, he enunciated a new doctrine applicable to all Arab countries. The US, he said, "has been clear that we stand for a set of core principles. We believe the universal rights of the Egyptian people must be respected, and their aspirations must be met." Universal means Libya, too. Now the Libyan opposition waits to see how Obama will show his doctrine is more than mere words.

If the great powers do intervene militarily, the Libyan revolt may swiftly be transformed into a western war in the Middle East. Freedom from oppression, democratic self-determination and the defenestration of a hated dictator could take second place to western imperatives: ensuring regional stability, pursuing counter-terrorism, safeguarding oil supplies, and stemming a new surge of sub-Saharan immigration into southern Europe. This would be less a revolution, more a recolonisation. Gaddafi's (and al-Qaida's) propagandists would have a field day.

If the west does not intervene, and the revolution is bloodily suppressed, leaders who spoke out boldly and bravely in support will be ridiculed as impotent charlatans. They will not be trusted again. They may be forced, in time, to deal with a triumphant and unpredictably vengeful Gaddafi. And democratic uprisings elsewhere in the Arab world will be set back, perhaps fatally. It is a conundrum made in hell. Except it was made in Downing Street.