Moscow's police have enhanced security measures in the US embassy.
Traffic was blocked in Devyatinsky Lane in the centre of Moscow, the new location of the US diplomatic mission.
Interior forces servicemen and a communications vehicle arrived. The total of 420 people, including OMON (a special purpose police unit) were involved to ensure order, Moscow's GUVD (the Main Interior Affairs Department) reported.
Wednesday and Thursday witnessed unsanctioned anti-war rallies in front of the embassy, held by KPRF and Liberal-Democratic MPs, meeting with their electorate. No incidents took place there.
It was reported on Friday that the rally had gathered 500 protestants, a spokesman for the GUVD said.
The discovery of the submarine has unveiled a few "inconsistencies." For example, how can one explain the fact that the sub was found where it needed to be searched for from the start?