The training ship "Smolny" and a Steregushchiy class frigate were both recorded inside Latvia's exclusive economic zone but 14.5 and 10 nautical miles respectively from the sea border.
LV ekskl. ekonom. zonā 14.5. j.j. no terit. jūras bruņotie spēki 02.03.identificēja RU BS mācību kuģi "Smolny"— NBS (@Latvijas_armija) March 3, 2017
LV ekskl. ekonom. zonā 10. j.j. no terit. jūras bruņotie spēki 02.03.identificēja RU BS Steregushchiy klases fregati— NBS (@Latvijas_armija) March 3, 2017
The preceding ID was on March 1 when another ship of the Steregushchiy class was spotted just over 3 nautical miles from the sea border -- though that one was designated a corvette, not a frigate. As this article explains, both appelations can be given to this type of vessel, which is one of the most flexible and modern in the Russian fleet.
LV ekskl. ekonom. zonā 3 j.j. no terit. jūras bruņotie spēki 28.02. identificēja Krievijas BS Steregushiy klases korveti— NBS (@Latvijas_armija) March 1, 2017
Some details of this class of vessel are given in the video below.