In the 1990s and 2000s, as more soldier began wearing bulletproof vests with hard ceramic armor, the machine pistol became less useful in a military setting. The low-powered pistol ammunition was not able to penetrate ceramic-plated Kevlar military vests. As a result, armies began to issue a new gun, the personal defense weapon or PDW. The PDW fires armor-piercing, higher-powered ammunition which can go through bulletproof vests.