The Atlantic publishes a list of 22 countries that have no formal armed forces, no military, which is not to say that their police are unarmed. Many of them are tiny island nations nobody is likely to invade, and others like The Vatican or San Marino are embedded within another nation (both of these within Italy) which provides for their external defense as it defends itself.
On the other hand, two are countries of consequence: Costa Rica and Panama. This interesting phenomenon is part of a larger pattern of small countries basically having few to no troops and weapon systems, or perhaps a ceremonial guard regiment or two. Many effectively have decided to allow the U.S. to defend them, gratis, meaning you and I pay for their defense.
