Nearly six months after securing a United Nations Security Council resolution authorizing a no-fly zone in Libya and the use of "all necessary measures... to protect civilians and civilian populated areas under threat of attack," the US and its NATO allies, former colonial powers, are mounting a barbaric siege of a major population center that threatens to produce civilian casualties on a mass scale.

In their breathless promotion of the "final battle" to realize the real US-NATO aim in Libya - regime-change - few in the Western media have bothered to consider the fact that the major imperialist powers are carrying out precisely the kind of act they claimed their war was designed to prevent.

Gaddafi's troops were marching on Benghazi, the world was told, and only a "humanitarian" intervention by NATO could save the city's innocent population. Now the "rebels" are encircling Sirte, led by British and Qatari special forces troops, intelligence operatives and mercenary military contractors, while the city's population is being pounded by NATO bombs and cut off from food, fuel and all basic supplies.

The sheer contempt shown by the US and the Western European powers for legality and world public opinion is breathtaking. The pretense that NATO is acting under the terms of the UN resolution that provided a fig leaf for its intervention is more than absurd; it has become obscene.

One has to go back to the crimes of the fascist powers in the 1930s and 1940s to search for parallels to such a siege: the bombing of Guernica in the Spanish Civil War, the siege of Leningrad and the Warsaw Ghetto.

NATO warplanes have over the past few days conducted scores of air strikes against Sirte, the town of Bani Walid to its west and the roads linking the two. While there have been no independent reports from Sirte, the spokesman for the Gaddafi regime, Moussa Ibrahim, reported that the continuous bomb and missile attacks have killed 1,000 people in the city and left many more wounded.

Part of this ferocious air assault is aimed at assassinating Colonel Muammar Gaddafi, who is believed by some to have taken refuge in the city or its surrounding area. Western special forces are reportedly on the ground hunting for Gaddafi, while an array of US spy planes have been deployed to pinpoint his whereabouts.

The NATO-led rebels have taken up positions on the main coastal highway both east and west of Sirte, with orders to stay in place until the NATO blitzkrieg has sufficiently annihilated the city's defenders.

The National Transitional Council (NTC), the self-appointed body of ex-Gaddafi ministers, Western intelligence assets, Islamists and tribal functionaries that has been recognized by the major powers as the legitimate government of Libya, has announced a surrender-or-die ultimatum to the city. If a surrender is not forthcoming by Saturday, they say, the city will be subjected to military assault.

"We have been given no indication of a peaceful surrender," an NTC military spokesman, Col. Ahmed Omar Bani, told a press conference in Benghazi. "We continue to seek a peaceful solution, but on Saturday we will use different methods against these criminals."

"Sometimes to avoid bloodshed you must shed blood, and the faster we do this the less blood we will shed," said Ali Tarhouni, the deputy head of the NTC.

The Western media is justifying a bloodbath in advance, reporting that the "rebels" have "unfinished business" or "scores to settle" with Sirte's defenders, which are said to include army units involved in the attacks on Misrata and Benghazi. The city is also Gaddafi's hometown and a center of his tribe, the Gaddafifahs.

The criminal methods employed by NATO and its "rebel" proxies - the bombing of cities, attempted assassinations, massacres and the lynching of black sub-Saharan African immigrant workers - are in sync with the aim of the war: imperialist conquest.

Having supported the Western-backed dictatorships of Zine El Abidine Ben Ali in Tunisia and Hosni Mubarak in Egypt against popular revolts until the bitter end, the US and its NATO allies decided to intervene in Libya, which lies strategically between these two countries. They set about hijacking the anti-Gaddafi demonstrations that broke out last February and fomenting a civil war as a vehicle for direct NATO intervention. To this end, British and French special forces units were deployed on the ground in Libya well before any UN resolution was ever discussed.

This intervention was never about protecting the civilian population. Tellingly, a spokesman for the NTC Wednesday estimated that the total number of Libyans killed in the last six months - both civilians and combatants - has risen to over 50,000. If one were to accept as good coin the pretense that NATO waged its war for the purpose of saving human lives, it would have to be judged a colossal failure. This war has produced far more carnage than any repression that preceded it.

The goal of the NATO war is to install a puppet regime in Tripoli that will be a more pliant tool of the Western governments and energy conglomerates. Ruling circles in Washington, London, Paris and Rome are salivating over the prospect of turning the clock back 42 years to the days when the corrupt monarchy of King Idris let Standard Oil write Libya's petroleum laws and provided military bases to both the US and Britain.

Consolidating such neocolonial aims will no doubt entail an even greater amount of bloodshed in suppressing popular opposition within Libya.

The crimes being carried out against the people of Libya and the threat of a far wider conflagration that is inherent in the inter-imperialist tensions over who will control the country's oil wealth pose the urgent necessity of a new antiwar movement, based on the working class and a socialist perspective.

The struggle against war must be joined with the fight against the assault on jobs, living standards and basic social and democratic rights taking place in virtually every country. It must be consciously directed against the source of both militarism and the unfolding social counterrevolution - the capitalist profit system.