The defendants are accused of being so-called “illegals”, working for the Russian foreign secret service under false identities to penetrate US government policy-making circles.
However, Sergei Lavrov, the Russian Foreign Minister, has accused the US of remaining silent over the string of arrests on Sunday evening.
During a visit to Jerusalem, Mr Lavrov said: “The subject was not explained to us. I hope they will explain.”
The scandal follows a bilateral summit between President Dmitry Medvedev and US President Barack Obama earlier this month that was designed to underscore warming ties between the two Cold War adversaries.
At the time, Mr Obama praised his Russian counterpart as a “solid and reliable partner” and took him out to a burger restaurant.
Referring to the arrests, Mr Lavrov added: “The choice of timing was particularly graceful.”
The FBI accuses the SVR, the successor organisation to the Soviet Union's KGB, of running a network of “illegals”, described in court documents as Russians who received training in languages, codes and ciphers, invisible writing and counter-surveillance before living in the United States under false identities.
Each of the 10 was charged with conspiracy to act as an agent of a foreign government, which carries a maximum penalty of five years in prison on conviction.
They were alleged to have met US government officials given codenames such as “Farmer”, “Parrot” and “Cat” as well as engaging such tried and tested espionage methods as dead drops and brush passes.