Iran recently announced that it has begun manufacturing, and issuing armor piercing bullets for the AK-47 type assault rifles used by their infantry. Iran claimed that these new bullets could penetrate protective vests. Actually, they can, and can probably penetrate over 10mm of armor. The Iranians claimed that these bullets can penetrate 20mm of armor, which is only true if you are using low quality armor. There's a lot of that in the region. But the ceramic plates used in American protective vests can stop at least one of these armor piercing bullets. These more expensive bullets have to be fired at close range (under a hundred meters) and in large quantity to guarantee they will overwhelm the body armor typically worn by American troops. However, if any American troops do get hit by this new Iranian ammunition, it will cause a stink that may prove expensive to the Iranians. The new Iranian bullets will, however, penetrate most protective vests worn by police.