Bush, talking to reporters covering his monthlong stay at his Texas ranch, said he still expects Liberian President Charles Taylor to leave the country before he will dispatch a larger American force.
"This is all part of doing what is necessary to help (West African troops), going in to provide the conditions necessary for humanitarian relief to arrive, whether it be by sea or by air," Bush said.
He spoke as he entered a favorite restaurant near his central Texas ranch.
Bush spoke with Secretary of State Colin Powell at his side, during a midday break from a long meeting they had on trouble spots around the world. Both men's wives stood nearby.
Both Bush and Powell said they want Taylor to leave the country.
Asked whether Taylor's departure was a condition for a larger U.S. deployment, Bush said: "Yeah, we would like Taylor out."
Powell added, "We still expect President Taylor to leave."
Administration officials have said they envision a force of up to several hundred bolstering the West African troops who began arriving Monday.
The Economic Community West African States organization is "starting to establish a sense of security and putting hope back in the hearts of the Liberian people," Powell said.
The administration sent a half dozen American Marines to assist West African peacekeepers, and they arrived Wednesday.
Three officials speaking on grounds of anonymity had said earlier that while an additional dozen or so could be added to that team, no decision has been made to send anything beyond 20 people.
"Do not look at this as a vanguard of more people to come," one official said.
One defense official said its possible that no U.S. peacekeepers will be sent to Liberia. Another said more troops might be considered if Bush's demands are met - that is, Liberian President Charles Taylor must leave the country and there must be a firm cease-fire in place.
Taylor has pledged to leave office Monday, but his government says he will go only when an adequate number of peacekeepers are on the ground - and a U.N.-Sierra Leone war-crimes indictment against him is dropped.
The small U.S. team that arrived Wednesday will serve as a liaison to the Africans, help them in a planned several-week buildup of their peacekeeping force, which began arriving Monday, and coordinate civilian contractors who are providing other logistical and humanitarian services.
Officials said the small contingent of troops, in a limited role and for a limited time, is designed to emphasize again that Africans should lead any effort to stabilize the nation torn by fighting by rebel forces and Taylor's troops.
Other U.S. assistance has included the promise of $10 million to contract with civilians who would do logistics at ports, with humanitarian assistance and so on, officials said.
West African leaders and U.N. Secretary-General Kofi Annan in late June asked the United States to send 2,000 troops to lead an African force of another 3,000, an idea the administration rejected in the ensuing weeks. Those seeking the troops had cited the historic U.S. relationship to Liberia, originally formed by freed American slaves.
There has been much U.S. activity since then, but much of it has been shrouded in secrecy. On Wednesday, Pentagon officials declined to provide information on the type of troops in the new liaison team, where they came from or what their skills are for the job.
Over the months of discussion about Liberia, some Pentagon officials said there was a plan to send 300 Marines to help with communications, transportation, logistics and so on - contingent on Taylor leaving Liberia.
Some 60 American troops were sent to augment security at the U.S. Embassy in the capital, Monrovia. They also evacuated some missionaries and others.
In early July, the U.S. military commander in Europe was ordered to begin planning for possible American intervention. Later, some 30 other Americans were sent in two teams to assess the humanitarian needs and the military situation in Liberia and more teams followed to neighboring countries to talk with African forces about their needs, capabilities and so on.
The Pentagon also sent a three-ship group with 2,000 Marines and 2,500 support sailors to stand by off the coast and be ready for any contingency, officials said. The group, headed by the amphibious assault ship USS Iwo Jima, is positioned less than 100 miles offshore. It was unclear if those troops would have a role in Liberia.
Officials said the newly arrived team would report back to the U.S. commander of the amphibious group.
The West African peacekeepers already are bringing a measure of calm to the country.
Taylor, then a warlord, launched the civil war in 1989 that has ravaged the tiny nation.