bergita said:
What is the name of your state?
can a person who is being petitioned for immigration by a war veteran parent visit the US as a tourist without affecting his petition?
That person is as welcome to visit as any non-USC. They should carry evidence of their ties to their home country should the border agent question his/her intent to remain in the US.
If the visit is late in the petition/visa app process, an additional name check -may- be required, slowing down total processing time, but there is no hard evidence of when that additional name check might be called for.