Unfortunately, The Bush administration has no interest in confronting Iran or Syria militarily.
I don't think that is a fair statement.
He doesn't however, have public support or Congresses support for doing so.
Nor do our allies support doing so.
However, since the AP is actually reporting this, maybe the media is starting to end (or loosen up on) their relentless attack on anything they think they can bash Bush with, and start giving a more accurate picture of what is happening in Iraq.
If the media starts showing the truth, and the public starts directing it's displeasure over the mess in Iraq more at Syria and Iran, Bush might have enough backing that Syria at least might start doing more to close it's borders to insurgents. Syria has been susceptible to such pressure in the past, more so than Iran.
If we can put our administration back in a position where they have the backing to even order limited strikes on Syria and Iran, it would likely have a large effect on Iraq.
Right now Syria and Iran are operating with very little fear of reprisal for their actions.
The Iraqis need to be the one yelling about how people from other countries are coming there to kill their citizens.
And, the Iraqis are the ones who need to take care of the trouble makers in a style well known in the ME.
Then Bush has lost.
The answer is obvious. Put the troops along the border with Syria. Anyone who tries to cross without authorization or has forged documents is immediately shot dead.
But like you said, the Bush administration won't confront Syria militarily. The US won't do that because our enemies, abroad and at home, won't like it.