WASHINGTON — The federal government may have ground to a halt because of the budget standoff in Washington, but at least one part of the government continues to operate as usual: foreign aid agencies.

While government workers in the United States have been furloughed, aid workers continue to provide services to millions of people from Africa to South America.

“The aid agencies, including the Agency for International Development, are considered part of the national security apparatus,” said Andrew S. Natsios, a professor at Texas A&M University’s Bush School of Public Service and a former administrator of U.S.A.I.D. “Both the Bush and Obama administrations’ national security strategies list development as a security issue.”

Mr. Natsios said that the aid agencies managed billions of dollars around the world, and that a sudden cutoff of financing would hinder American diplomacy and development efforts. It would also harm the agencies’ ability to respond to international humanitarian crises.

U.S.A.I.D. did not respond to a request for comment, but in its guidance memo on the government shutdown, top managers at the agency said it would continue as many operations as possible. Most of the aid agencies have multiyear appropriations or financing that is not tied to a fiscal year.

The agency said it continued to honor contracts and grants made before the shutdown. Previously scheduled travel will be honored, but not new travel, the agency said. New travel can be approved, but only in cases involving human safety, like providing food, medicine or other services to refugees.

But while American aid agencies are faring better than most government agencies, they have not been immune to the effects of the shutdown. Many workers in Washington have been furloughed.

And concerns have been raised by the hundreds of nonprofit organizations and the foreign governments that receive financing from the agencies. U.S.A.I.D. has assured contractors and grantees that the shutdown will not affect their programs, but it is unclear how long that will be the case.

“I think they will be O.K. for a while,” Mr. Natsios said. “But if the shutdown goes on for some time, that might change. The agencies may eventually run out of the money, and then we will start to see an impact on our development and diplomacy programs abroad.”