Anonymous sources

This morning on the front page the LAT has a piece by Greg Miller that totals roughly 3,000 words and is based entirely on anonymous sources. Miller claims that Osama bin Laden and Ayman Zawahiri are in western Pakistan and are receiving money from Al Queda in Iraq, without which they would be desperately short of funds. Miller also reports a CIA surge into western Pakistan in an effort to locate and capture the two Al Queda leaders. Some or all of this may be true but it also could be partly or wholly false. Who are Miller's sources and what are their motives? Why are they not willing to be named? Why does the LAT print "news" from unnamed sources? Why should we believe what the LAT reports? After all, the LAT has for years viewed events and facts from the left.