The United States has raised the stakes in the Middle East by warning Syria and Iran not to get involved in the Iraq war, and to follow what Secretary of State Colin Powell called "acceptable patterns of behaviour".
The significance of the American warnings is that they go well beyond the current conflict and concern the future policies of both countries.
The US appears to be trying to shape the political landscape of the Middle East for the post-war phase.
They also raise the question as to whether action in some form against other countries might follow the war against Iraq.
Powell's warning followed one from Donald Rumsfeld on Friday
Iran was named by President George W Bush as part of the "axis of evil". Both Iran and Syria are on the list of "states sponsoring terrorism" issued by the US State Department.
"Washington is laying down some red lines," according to Daniel Neep, head of the Middle East programme at the Royal United Services Institute, a defence think-tank in London.
"It could be the beginning of a more robust American policy," he told BBC News Online.
'More responsible behaviour'
The American approach is very different from that of Britain, which has made considerable efforts in recent months to be friendly with both Iran and Syria.
The US Under-secretary for International Security, John Bolton, who tends to say what others in the administration might be thinking, is reported to have told Israeli officials recently that the US would have to "deal" with Syria, Iran, Libya and North Korea after Iraq, though in what fashion he did not say.
The Americans are using strong language. In his speech in Washington to the main pro-Israeli lobby group, the America Israel Public Affairs Committee, Mr Powell said that the US wanted to see "more responsible behaviour", a diplomatic phrase meaning a radical change of policy.
He made specific demands. "Syria faces a critical choice," he said.
Tehran must stop pursuing weapons of mass destruction and the means to deliver them
US Secretary fo State Colin Powell
"(It) can continue direct support for terrorist groups and the dying regime of Saddam Hussein or it can embark on a different and more helpful course."
And his message to Iran went further. Not only did he say that "Iran (must) end its support for terrorism", but he added: "Tehran must stop pursuing weapons of mass destruction and the means to deliver them."
By "terrorist groups", Mr Powell means the Lebanese Hizbollah and the Palestinian Hamas and Islamic Jihad.
His comments followed warnings from the US Defence Secretary Donald Rumsfeld, who said last Friday that military equipment including night-vision goggles had been getting to Iraq from Syria, and that the Syrian Government would be held "accountable for such shipments." Syria has denied any responsibility.
Mr Rumsfeld also told Iran that Iranian trained Shia fighters opposed to Saddam Hussein, some of whom have entered Iraq, would be treated as "combatants" if they posed a threat to US forces.
So there is no doubt of the concerted nature of the American statements.
There has been an angry reaction from Damascus and Tehran.
The Syrian Foreign Minister Faruk al-Shara declared: "Syria's interest is to see the invaders defeated in Iraq. The resistance of the Iraqis is extremely important. It is a heroic resistance to the US-British occupation of their country."
The Iranian Foreign Minister Kamal Kharrazi said: "From the very beginning we predicted that the Iraq nation would not welcome foreign invading forces. They (the Americans) are seeking to ensure Israel's complete domination over the region."
Neither Syria nor Iran has any love for Saddam Hussein. Syria, which for years vied with Iraq for leadership in the Arab world, joined in the first Gulf War in 1991 and Iran had to defend itself for eight years in the war Saddam Hussein launched in 1979.
Both countries have been trying to steer a careful course between opposing this war and not supporting Saddam Hussein. They are conscious that their peoples are against the war
Both countries have been trying to steer a careful course between opposing this war and not supporting Saddam Hussein. They are conscious that their peoples are against the war.
"Syria had hoped to retain a free hand, "said Mr Neep. "It supported the war on terrorism as it is against Islamic terrorism, but it is supporting the Palestinian groups. The US is now fed up and is laying down the law."
As for Iran, says Mr Neep: "Elements had been trying to get a rapprochement with the United States but this is now very unlikely. The US has said clearly that it will brook no interference."