How the United States is dealing with terrorism suspects beyond those already in the prison at Guantánamo Bay, Cuba, was a question Mr. Obama did not address in the speech he gave Thursday about his antiterrorism policies. While he said he might seek to create a new system that would allow preventive detention inside the United States, the government currently has no obvious long-term detention center for imprisoning terrorism suspects without court oversight.

Mr. Obama has said he still intends to close the Guantánamo prison by January, despite misgivings in Congress, and the Supreme Court has ruled that inmates there may challenge their detention before federal judges. Some suspects are being imprisoned without charges at a United States air base in Afghanistan, but a federal court has ruled that at least some of them may also file habeas corpus lawsuits to challenge their detentions.

American officials say that in the last years of the Bush administration and now on Mr. Obama’s watch, the balance has shifted toward leaving all but the most high-level terrorist suspects in foreign rather than American custody. The United States has repatriated hundreds of detainees held at prisons in Cuba, Iraq and Afghanistan, but the current approach is different because it seeks to keep the prisoners out of American custody altogether.

How the United States deals with terrorism suspects remains a contentious issue in Congress.

Leon E. Panetta, the director of the C.I.A., said in February that the agency might continue its program of extraordinary rendition, in which captured terrorism suspects are transferred to other countries without extradition proceedings.

He said the C.I.A. would be likely to continue to transfer detainees from their place of capture to other countries, either their home countries or nations that intended to bring charges against them.

As a safeguard against torture, Mr. Panetta said, the United States would rely on diplomatic assurances of good treatment. The Bush administration sought the same assurances, which critics say are ineffective.

A half-dozen current and former American intelligence and counterterrorism officials and allied officials were interviewed for this article, but all spoke on the condition of anonymity because the detention and interrogation programs are classified.