US B-52 warplanes have bombed the Iraqi front line between the town of Dohuk and the city of Mosul in the north of the country.
A Reuters reporter said he saw the Americans make at least three sorties, dropping about half a dozen bombs each time. Plumes of smoke billowed above the horizon in the direction of Mosul, he said.
He also said he saw a convoy of about 25 Turkish-registered trucks heading south along the road towards Dohuk this morning with a US military escort. A US soldier accompanying the convoy declined to say what the trucks were carrying or where they were headed.
The Iraq-Turkey border has been closed since before the United States and Britain launched their war to topple President Saddam Hussein on March 20th.
The United States has deployed a small number of troops in northern Iraq to operate alongside the Kurdish fighters opposed to Saddam's rule.
Last month, in a big setback for Washington, Ankara's parliament denied permission for up to 62,000 US troops to use Turkish territory to open a "northern front" against Iraq.
Ankara has reserved the right to bolster its own small military presence in northern Iraq if it sees a danger of the Kurds establishing an independent state that, it believes, would rekindle armed Kurdish separatism in Turkey's southeast.
US Secretary of State Colin Powell is visiting Ankara today to seek Turkey's agreement not to send a large force into Iraq for fear it could undermine the US-led war.