The US has now amassed a military force of 28,000 troops, more than 300 warplanes and two dozen warships in the region surrounding Iraq and Afghanistan, enough firepower to allow President Bush to strike at any moment should he so decide.
The diverse forces, stretching from the Indian Ocean to the Red Sea, bring a potent range of military options with them to keep pressure on those two isolated nations. But senior Pentagon officials acknowledge that those options are in many ways both imperfect and risky.
New kind of war
Although Bush and Defense Secretary Donald Rumsfeld say the campaign against terror will be a new kind of war, the force in the region still relies predominantly on air power, with all its limitations, the officials said. Conventional wars are ultimately won by taking and holding territory, as one military maxim has it, but that is not an option being considered now.
The Pentagon has also mobilized special operations troops -- their numbers are secret -- but they are now playing mainly a supporting role to possible air and missile strikes, the officials said.
For now, other ground forces are most likely to play mainly protective roles in places like Kuwait.
Air power
The US has recently dispatched B-52 and B-1 bombers to the region and has Navy F-14s and F-18s aboard nearby aircraft carriers. Air Force F-15s routinely enforce no-flight zones over Iraq, where American and British warplanes have continued to skirmish with Iraqi air defense forces even since the Sept. 11 terrorist attacks.
So far, the Bush administration has resisted temptation to retaliate immediately for the attacks on the World Trade Center and the Pentagon as it rallies broader international support for battling terrorism and gleans intelligence on the whereabouts of Osama bin Laden and his allies.
The question of how to battle terrorists in their remote and rocky Afghan havens has perplexed military planners in both the Clinton and Bush administrations, some of whom share a darkly comic answer when asked about the war plan.
"It's called AOS," they say, using a barracks retort for "all options stink." Another senior military official said there was "no good option that wouldn't make us look useless."
Even a series of precisely calibrated strikes would require a vast and expensive network of bases, command posts, flight decks, refueling outposts and defensive weapons, with all the accompanying logistics.
A senior Air Force officer said late this week that the Bush administration was still negotiating for all the support for overflights and for basing aircraft it would like in the region.
John Bolton, the undersecretary of state, ended the week in talks with Central Asian countries that border Afghanistan.
A senior official said that negotiations this week in Pakistan had given the US significant access to bases there, mainly for search and rescue operations.
"Some people were actually pleasantly surprised how much they agreed to," a Pentagon official said.
Ever since the Persian Gulf War in 1991, the US has maintained a significant military presence in the region, largely to keep President Saddam Hussein of Iraq in check.
At any given time, those forces number more than 20,000 troops, nearly 200 fighter and support aircraft and at least one aircraft carrier and its accompanying warships, which include submarines, cruisers and destroyers able to fire scores of long-range cruise missiles.
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