"Every day in central Tallinn… a team of five people hired by the Americans for drafting reports on potential dangers is watching the people's movements," the Estonian Postimees outlet writes.
The paper adds that the amount of reports reaches five to six on a monthly basis, depending on the level of activity.
"This is part of normal security measures, as the safety of our staff and guests — both Estonian and American — is a priority for the US government," Bradley Hurst was quoted by the outlet.
The legality of the practice was affirmed with the Estonian government in advance, he added.
Former NSA contractor Edward Snowden's 2013 document leaks revealed systematic surveillance of German Chancellor Angela Merkel's private phone calls as part of the SCS program, leading to an ongoing global diplomatic scandal.