Invisible gun

Heard just now on the BBC's Ten O'Clock News:

For the gunmen in Fallujah, the noose is tightening.

As this phrase appeared to refer purely to the Iraqis, I have to assume that the American soldiers assaulting the city are not using guns. What, I wonder, can they be doing instead?

• Are they using peashooters?
• Have they resorted to the employment of bows and arrows?
• Do they propose to overcome their enemies by the judicious deployment of irony?

I think we should be told.