Germany
Lincoln
No
An immigrant in the US can petition for his or her spouse who lives in a foreign country as long as he/ or she living in the US has already recieved their citizenship.
No foreign country owns any part of a US state.
france
Of the US, Canada.
Canada if you are from the US and the US if you are from Canada.
A president kind of deals with trading with the foreign country. A president also wants to have a good alliance with the foreign country so that if our country needs any help, the other country our president has an alliance with can help us.
There are two possibilities here: the US Anbassador assigned to that country and the US Secretary of State.
If the foreign citizen is in the US and violates a treaty of the US, he/she can be brought in a US court. Otherwise, if the citizen is in another country, the court of that country is responsible for that violation.
Foreign investors already invest in the US, and have since the founding of the country.