BAGHDAD - US soldiers killed at least 29 insurgents in a drive to root out militants in western Iraq, the military said on Friday, after US President George W. Bush vowed not to waver in his campaign against Islamic extremists.US officials said their latest campaign near the Syrian border was scoring successes as about 1,000 soldiers backed by combat aircraft seek to shut down what they say is a key route for arms and fighters into the country. US officials say the western Iraq campaign will last at least through December, seeking to turn back rising insurgent violence before an Oct. 15 referendum on a new constitution and a vote in December for a new parliament.