But then since the NSA spies on all Americans all the time, anyway, it is rather a moot point.
I am pretty sure it is the in the job description of the NSA to intercept and monitor calls and mail made to heads of foreign powers
yep
Bush signed a presidential order in 2002 allowing the National Security Agency to monitor without a warrant the international (and sometimes domestic) telephone calls and e-mail messages of hundreds or thousands of citizens and legal residents inside the United States.
The program eventually came to include some purely internal controls - but no requirement that warrants be obtained from the Foreign Intelligence Surveillance Court as the 4th Amendment to the Constitution and the foreign intelligence surveillance laws require.