I tried checking online to see exactly what the age of criminal responsibility was in USA. thie page says:
United States of America

The minimum age of criminal liability is set at the federal and state level in the United States. At the state level, 33 states set no minimum age of criminal responsibility, theoretically allowing a child to be sentenced to criminal penalties at any age [Cipriani,D. Children's Rights and the Minimum Age of Criminal Responsibility: A Global Perspective, Ashgate 2009, p. 221 and 222], though in most of these states a capacity related test is applied.


So, basically, in US, if you can commit a crime, you risk being punished for it. As long as the children are aware of this, it seems reasonable. Of course, there will be those who do not understand the possible consequence of their actions.