Oh come on!
Understandably, the Russian press has taken interest in Siil 2018, running the headline “largest military exercise” frequently. For a country of fewer than 1.5 million people, these statistics and headlines are indeed impressive. Some Russian commentators have discussed the possibility that the Baltic States are preparing their own aggression against Russia, either literally or by simply conducting these exercises in regions with Russian-speaking populations.
However, how does a 15,000-strong exercise stack up against Russian military exercises? It should be noted that most of the 13,000 Estonians participating in Siil 2018 come from the Estonian reserves (Kaitseliit).
This is a recent article about a 2018 NATO exercise in Estonia. The whole purpose was to practice not being rapidly overrun while hoping for help from the rest of NATO in the face of overwhelming Russian numbers and weapons at the point of contact.
That is, while NATO is more powerful than Russia, most of NATO's power is far from the eastern frontiers of NATO where Russia can generate a short-term decisive advantage.
Russia should be embarrassed to even hint that the exercise made them wet their pantskies. Perhaps they reveal more than they'd intended.
UPDATE: Gerasimov emits an "eek" too:
NATO exercises near the border with Russia reflect the alliance’s preparations for a large-scale military conflict, Russia’s chief military officer said in remarks published Wednesday.
Although to be fair, he is correct--NATO rightly worries about Russia initiating large-scale military operations with an invasion of NATO Baltic states.