The US Secretary of State, Mr Colin Powell, has warned Iran to cease trying to develop weapons of mass destruction, and both Iran and Syria to end their support for terrorism, writes Conor O'Clery, North America Editor.
Syria's leadership faced a critical choice and would be held responsible for any assistance to Iraq in the war, Mr Powell said in an address to the American Israel Public Affairs Committee.
By choosing the forum of a pro-Israel lobby for his warnings, Mr Powell may have underlined Arab suspicions of American identity with Israeli interests in the region.
But the chief US diplomat also used the occasion to press home another message less popular with the audience.
As terrorism subsided, Jewish settlement activity on the occupied territories must end, Mr Powell said.
This echoed what President George Bush had said in his pre-war promise to publish the long-awaited "road-map" for the creation of a Palestinian state by the end of 2005.
Mr Powell said movement would begin on the road-map after Mr Mahmoud Abbas was confirmed as Palestinian prime minister in the coming days.
The road-map, drawn up by the US, the EU, Russia and the UN, calls for a secure Israel living side by side with a peaceful Palestine.
Mr Powell said the road-map was not an "edict", but a statement of the broad steps the US believed Israel and the Palestinians must take.
The response from the large audience at the function in a Washington hotel to the prospect of an end of settlement activity was reported to be mixed, with mild applause and some booing.
There was silence and some hissing when the Secretary of State said Israel "must take steps to ease the suffering of Palestinians and diminish the daily humiliation of life under occupation."
A much more enthusiastic response greeted Mr Powell's warnings to Iran and Syria, first made by the Secretary of Defence, Mr Donald Rumsfeld, on Friday, suggesting a more assertive role for the US in the Middle East beyond Iraq's borders.
Mr Rumsfeld accused Syria on Friday of supplying military technology to Iraq, a charge Syria has denied.
"Syria can continue direct support for terrorist groups and the dying regime of Saddam Hussein, or it can embark on a different and more hopeful course," Mr Powell said.
"Either way, Syria bears responsibility for its choices and for the consequences."
On Sunday the Syrian Foreign Minister, Mr Farouk al-Sharaa, said: "Syria has a national interest in the expulsion of the invaders from Iraq."
Mr Powell demanded that Iran "stop its support for terrorism against Israel" and "its pursuit of weapons of mass destruction and the ability to produce them."
Referring to the debate that has engulfed Washington about alleged setbacks in the US-led invasion of Iraq, Mr Powell endorsed the Pentagon's current war plan.
"I have total confidence in the plan and total confidence in Gen Franks and those carrying out the plan," he said.