OGOTÁ, Colombia, Aug. 19 — Defense Secretary Donald H. Rumsfeld, on a one-day visit to Colombia, said today that the United States would support Colombia in resuming a policy that allows Colombian fighter pilots to shoot down planes suspected of ferrying drugs or force them to land.
Such a policy, which has been criticized by human rights groups, was suspended in Colombia and Peru after a Peruvian jet fighter mistakenly shot down a private plane carrying American missionaries, killing two people, one an infant, in 2001.
A White House statement said President Bush had determined that Colombia had since "put in place appropriate procedures to protect against loss of innocent life."
The announcement did not specify those safeguards, but American officials said they would include radio or visual contact, first trying to force suspect planes to land, and then firing warning shots. Only as a last resort, American officials said, would a plane be downed.
"Some of these procedures existed in the old program," one American official said, "but they were not enforced."
A much more limited program, still being developed, may be put in place in coming months in Peru, officials said.
The announcement was timed as part of a visit to Colombia by Mr. Rumsfeld, who arrived in Bogotá, the capital, this morning under tight security to underscore American support for President Alvaro Uribe.
The Uribe government has received $2.5 billion from Washington, largely in military aid, since 2000 as it battles leftist rebels and drug traffickers. Colombia is likely to get $700 million more this year.
The Colombian drug trade, which supplies most of the cocaine entering the United States, has been increasingly tied to both the leftist insurgency and right-wing paramilitary groups. To move the drug, traffickers have often relied on private aircraft.
"There are plenty of ways that illegal trade can move — land, sea or air — and if you're not attentive to the air, it becomes a preferred method," said Mr. Rumsfeld, who was traveling with reporters.
As in the past, the American role in the drug interdiction plan will consist of working closely with Colombian officials to identify suspect planes, American officials said.
Under the new policy, coordinates from United States and Colombian radar stations will be passed on to Colombian crews flying Cessna Citation surveillance planes. The surveillance planes will then direct Colombian Air Force jets toward the suspect aircraft.
The surveillance planes will have at least one bilingual observer, most likely an American, to maintain contact with radar operators and Colombian Air Force commanders, American officials said. The pilots have also undergone extensive language training.
This American role will be overseen by the State Department, which has taken over the program from the C.I.A. The State Department has contracted with Arinc, a Maryland-based aviation company, to train Colombian pilots for the surveillance aircraft and other technicians. Previously, the work was conducted by DynCorp, another company with close links to the C.I.A.
Officials said orders to shoot down a plane could come only from Colombia's air force commander, Gen. Héctor Fabio Velasco, and planes would have to be within Colombian airspace.
Human Rights Watch officials, who have met with American and Colombian officials to raise concerns, say the program violates United States law-enforcement principles on use of force, which are limited to imminent threats.
"To use force is equivalent to an extra-judicial execution," said José Miguel Vivanco, director of the Americas division of Human Rights Watch.
Mr. Vivanco also criticized General Velasco's role. Some American officials have been prodding Mr. Uribe to dismiss Mr. Velasco because of the air force's role in the 1998 bombing of the village of Santo Domingo, in which 18 civilians were killed.
Washington has banned aid to the air force unit responsible for the bombing.
The air interdiction effort began in Peru in the early 1990's and quickly had a crucial effect in the drug war in the Andes.
Drug traffickers had used small private planes to ferry coca paste, the main ingredient for cocaine, from Peru to the Colombian jungle labs that manufacture cocaine. About 40 planes were shot or forced down in Peru, and others were seized on the ground. Increasingly traffickers shifted to ground or river transportation.
But on April 20, 2001, a Peruvian fighter shot down a plane carrying a group of American missionaries, killing Veronica Bowers and her baby daughter, Charity. A State Department report later found that the shooting had been caused, in part, by a language barrier, lack of oversight and the use of short cuts and improvisation during missions.
The downing not only raised serious questions about the lack of safeguards, but also deeply troubled American officials about future lawsuits, said officials familiar with the policy.
Those concerns helped delay a new program, said Phillip McLean, a former deputy assistant secretary of state for South America who helped negotiate the shoot-down policy with Peru in the mid-1990's.
"They wanted to make sure that the thing was put together to protect them," he said.
Mr. Vivanco said the fear of lawsuits has led American officials to shift more of the responsibility to Colombia. Indeed, the American official emphasized that the Colombian government, not the United States, would oversee the program.
"The U.S. knows for sure that they cannot protect themselves from domestic litigation," said Mr. Vivanco.
American officials and Mr. McLean said the Colombian government had been careful about downing planes even before the incident in Peru. Before the suspension in 2001, the air force here mainly focused on disabling aircraft on the ground.