The US Defence Secretary, Donald Rumsfeld, has again warned Iran not to interfere in Iraq.
By Nick Childs
BBC Washington correspondent
His remarks come against a background of continuing tough rhetoric from Washington directed at Tehran.
Some US officials want a tougher approach to Iran
There is little doubt that Washington is keeping up the rhetorical pressure on Tehran, but it is far from clear whether it amounts to anything more than that at this stage.
There is talk of moves within the administration to take a tougher line on Iran - not least from the Pentagon.
But there is no sign yet that that has been translated into a new policy approach.
It may all simply be designed to keep the Iranian leadership on its toes.
The trouble for the administration is that it is causing some unease among critics in Congress too.
Debate goes on
As so often, Mr Rumsfeld has led the rhetorical charge.
But when he talks of aggressively putting down any effort to remake Iraq in Iran's image, he is probably still thinking about measures in Iraq itself, not against Iran directly.
Other administration officials say Tehran has not done enough to crack down on al-Qaeda members they say are in Iran, and they have again voiced their suspicions about Iran's nuclear programme.
For the moment, it seems, the debate in the administration over whether to adopt a tougher overall line on Iran goes on.