US forces shot down an Iranian drone aircraft that ventured inside Iraq last month, US and Iraqi officials said on Monday.
An American military spokesman said that US jet fighters shot down the unmanned Iranian aircraft on 25 February, about 100 km northeast of Baghdad.
Lieutenant-Colonel Mark Ballesteros said coalition air forces tracked what is believed to be an Iranian "Ababil 3" drone for more than an hour before shooting it down.
He said the plane's entry was not an accident accident because of the distance into Iraq the drone flew and how long it stayed.
However, Major-General Abdul Aziz Mohammed Jassim, head of military operations at the Iraqi Defence Ministry, told Reuters he believed the plane's entry into Iraq was probably a mistake.
The three weeks of silence from US, Iraqi and Iranian officials about the unusual incident underscores the sensitive nature of any contact between Iran and the United States.
Iranian officials had no immediate comment on the incident.
The US military has long accused Iran of arming militants and meddling in neighbouring Iraq, where tens of thousands of people have died in sectarian and insurgent violence since the US-led invasion to oust Saddam Hussein in 2003.
But relations between the government of Iraq's Shi'ite Muslim Prime Minister Nuri al-Maliki and Iran, a fellow majority Shi'ite nation, are mostly friendly.
The two countries fought a bloody eight-year war in the 1980s which killed an estimated one million people, but ties have warmed since Saddam, a Sunni Muslim, was removed from power.