A hand grenade found close to George W Bush during his visit to the ex-Soviet republic of Georgia was armed and could have gone off, an FBI agent has said.
Bush received an enthusiastic welcome in Georgia
Bryan Paarmann also said the device had been hurled before falling into the crowd listening to the US leader's speech in the capital, Tbilisi.
It was found 30m (100 feet) from the stage in Freedom Square.
Georgian officials had said earlier that the grenade was inactive and had posed no danger to Mr Bush or others.
Speaking in Tbilisi, Mr Paarmann said the grenade, wrapped in a dark handkerchief when it was thrown, had "simply failed to function".
"We consider this act to be a threat against the health and welfare of the president of the United States, as well as the welfare of the multitudes of Georgian people who turned up for this event," the FBI agent said.
Reports said the grenade was an RGD-5, which has a reported range of 20-25m, according to Jane's Infantry Weapons.
Mr Bush's speech, delivered with Georgian President Mikhail Saakashvili at his side, was attended by tens of thousands of people who applauded loudly.
Georgia's security chief had said there was no chance the grenade could have exploded, and that the intention was probably to create public fear.
"The goal is clear - to frighten or to scare people and to attract the attention of the mass media," Gela Bezhuashvili told reporters.
"In any case there was no danger whatsoever for the presidents."