DUBAI – Al Qaeda’s Yemen-based wing vowed to “bleed” U.S. resources with inexpensive, small-scale attacks that cost militants just thousands of dollars to mount but billions for the West to guard against.

Al Qaeda in the Arabian Peninsula said it had spent just $4,200 on two parcel bombs mailed from Yemen to the United States last month. The bombs were intercepted in Britain and Dubai, sparking a world­wide security alert.