If the United States does decide to go to war in the New Year, all the signs are that it will be an all-out assault against Iraq as a whole, intended to destroy the Saddam Hussein regime and its military capabilities. Yet, there is increasing concern over the outcome of a war and the extent of allied casualties.

They will have, at most, six weeks before weather conditions deteriorate, first the rains in March and then the heat of summer, making combat increasingly difficult. But overlying this is the fear that the Iraqi armed forces will prove difficult to defeat and that the Saddam's regime has some unpleasant forms of retaliation available.It is now recognized that the most significant strategic event of the crisis was Iraq's peace settlement with Iran, allowing Iraq to re-deploy well over 200,000 troops away from the Iranian border.

This upset all the United States' planning assumptions and led the U.S. Chief of Staff Gen. Colin Powell to order a near doubling of U.S. forces when he visited the gulf last month.

Although the Pentagon's Central Command, which covers the Middle East, had had plans to move up to 300,000 troops to the gulf, the need for even more troops has strained resources badly.

The entire Desert Shield operation is now put at $25 billion to $30 billion for the current financial year, but costs would go through the roof if it came to war.

Such a war is now thought likely to start with heavy air attacks on Iraq for up to five days, involving at least 6,000 sorties, but even this overwhelming allied airpower is unlikely to make a war a short-term affair.

In addition to the 304,000 troops in and west of Kuwait, Iraq has 219,000 in the Basra area, including four elite Guards divisions. Most are in heavily defended positions, backed by over 2,800 artillery pieces.

Contrary to earlier reports, sanctions do not seem to have degraded Iraq's military capabilities so far; indeed, this could take several more months.

The level of casualties now anticipated by the allied forces is indicated by the medical provision for the British forces, making up barely 5 per cent of the total forces. The British army alone has 1,200 personnel in its medical command, with more on the way and reservists now being called up.

The field hospitals are reported to be able to handle at least 3,000 casualties a month, and extensive provision is being made for treating the wounded at National Health Service hospitals in the United Kingdom. In an all-out war, it is believed that up to 1,000 U.K. soldiers will be killed in the first 30 days.

For the United States, estimates range up to 12,000 dead and more than 35,000 injured, but this is assuming that the conflict is manageable. For the Iraqis, military and civilian casualties could exceed 130,000 dead and 400,000 injured, and it must therefore be expected that a regime facing these kinds of losses will be prepared to enact extreme responses.

While the Iraqis' main military response will be a bitter defensive war, they will also attempt offensive actions aimed primarily at civil and economic targets inside the gulf and in the United States and Europe. The former may involve air and missile attacks at cities and industry, especially oil installations, but will also rely heavily on sabotage by special forces units.

Outside the gulf, it is likely that similar units and also client terrorist groups are now in place. Their munitions will include conventional explosives such as Semtex but may also include chemical weapons such as nerve agents.

Likely targets will be those that simultaneously cause panic and economic disruption such as international airports and major railway terminals. No sponsoring state has yet armed terrorist groups with nerve agents, but no state has yet been in Iraq's position of facing massive military defeat. In such circumstances, "normal" behavior does not apply, and Iraq has shown itself to be remarkably inventive in recent months.

In the final analysis, allied military force would inevitably prevail, but at a huge cost. Victory would bring in its wake all the problems of maintaining occupation forces in Iraq while installing a client regime against a background of a bitter anti-American backlash in the Middle East and political controversy back home. As a result, President Bush remains in a huge dilemma and may well still accept a diplomatic compromise with all its awkward consequences.

Against this, the sheer size and momentum of the U.S. military buildup makes it increasingly difficult to avoid war, especially as the forces can be sustained for only a few months. Moreover, if a diplomatic settlement does appear likely, Israel is still waiting in the wings and may then intervene to prevent this and ensure the fulfillment of its primary security aim: the fall of Saddam and the destruction of Iraq's military forces.