WASHINGTON—Hostile forces in the Middle East are targeting American pilots with laser pointers at a growing rate, imperiling aircrews and reflecting a problem more widespread and longstanding than the Pentagon has previously acknowledged.

American pilots operating in Syria, Iraq and Afghanistan, the three most prominent conflict zones for American troops, experienced most of the more than 350 lasing incidents reported over the last seven months by aircrews operating across the Middle East, officials at U.S. Air Forces Central...