By Jonathan Marcus BBC defence correspondent

The US military is continuing to move men and equipment towards Iraq as the Bush administration signals that the time for diplomacy at the United Nations is fast running out.

Air strikes against Iraqi missile batteries and radars said to be threatening US and British aircraft patrolling the air exclusion zones over northern and southern Iraq have become more frequent.

The army is establishing a Qatar base which could be the HQ for an Iraq attack

All the signs are that the military build-up could accelerate dramatically over the next few months if the US administration decides upon military action against Iraq.

Whatever may have been happening at the UN, the US military has been working to a pre-determined timeline - one that envisages a potential conflict with Iraq early in 2003.

No decision on military action has been taken.

But the Pentagon's job is to ensure that, if President Bush makes that decision, the forces are in place to act upon it.

	:	Military balance
Iraqi and US forces in the region

The continuing military build-up serves an additional purpose of maintaining pressure upon Iraq - and indeed upon America's diplomatic allies at the UN, although the pressure does not seem to have had the desired effect there.

The US military has built upon its network of facilities in the Gulf and a pattern of established exercises to bolster its forces.

Navy movements

Three aircraft carrier groups could be deployed in the Gulf

Ships have been chartered to carry heavy equipment to the region, with some reports indicating that bridging equipment is included in the cargo - something that would be required for any operation against Iraq.

The movement of American aircraft carriers is always worth watching as a good indicator of impending military action:

• The USS Kitty Hawk has already departed from its base in Japan

• The USS Constellation and her battle group are due to leave port within a few days, which could see her on station in the Gulf by early December

• The USS Harry S Truman is starting its pre-deployment exercises and could also be on its way within a matter of weeks

Army exercises

US army exercises are already taking place in Kuwait.

And elements of Centcom - the headquarters that would command any war against Iraq - will be setting up shop in Qatar shortly.

January or February is still most pundits' estimate of when a war might start.

But, from early December, the US could have the capacity to pour troops and aircraft into the region with less than 10 days' notice.