A U.S citizen can be deported to the United States from another country. A U.S. citizen, even if they were not born in the U.S. but were naturalized, cannot be deported out of the U.S. The U.S. is the citizen's home country.
The example you provide involve people who are in the process of naturalization. But people who have completed the process are U.S. citizens.
A U.S. born U.S. Citizen cannot be deported, unless that person has given up his or her U.S. citizenship. Even then, it is fairly rare and would likely be treated as a novel situation.
However, a Naturalization U.S. Citizen can be deported, if the person committed fraud to obtain LPR status that was then perpetuated to fraud in obtaining citizenship or if the person committed fraud to obtain U.S. citizenship. In that case, the U.S. citizenship would first have to be revoked and then deportation proceedings undergone.
You may be interested in reading a 1997 Memorandum Opinion for the General Counsel of the INS on Revocation of Citizenship: http://www.justice.gov/olc/ina340.htm Furthermore, the Revocation of Naturalization laws (8 USC 1451) may be of interest to you: http://www.law.cornell.edu/uscode/8/usc_sec_08_00001451----000-.html
Finally, while it is not deportation, there are several acts that may lead to a loss of U.S. Citizenship:
1) Renunciation (giving it up);
2) Dual citizenship in a country that requires renunciation or a country that the U.S. requires renunciation to be a citizen in.
3) Treason conviction;
4) Holding public office in a foreign state; (rare, but possible)
5) Fraud during the naturalization process;
6) Refusal to testify before Congress about subversive acts within 10 years of being naturalized;
7) Serving in your native countries armed forces when engaged in hostile acts against the U.S.; and
8) Serving as an officer or a non-commissioned officer of another countries armed forces.
There may be other possibilities here too, but that is a short list of them options. Really, I don't recommend doing most of these acts.
If you are currently facing a case that may result in your deportation as a U.S. Citizenship, you should hire an attorney to assist you. This post is not legal advice and does not establish an attorney-client relationship.
A US Citizen cannot be deported. Period. We don't deport U.S. citizens, we send them to prison. A person who is in the process of naturalizing is not a U.S. cittizen and can therefore be deported is deportable under U.S. immigration laws.
If the government was to determine that an alien provided false/fraudulent information on his/her application for naturalization or obtained his/her residence unlawfully, the government can move a Federal District Court to revoke the citizen's certificate of naturalization. If this was to occur, the citizen would revert back to a permanent resident and possibly become subject to deportation.