As a member of NATO and the European Union, Estonia has always been guided by the principle that in its relations with third states, the aim is to foster common foreign and security policies of the alliance as well as the union, daily Postimees reported.

"The unity of Europe is of particular importance in relation to the communication of both Estonia other smaller border states with our eastern neighbor," Mr Terras said.

"Estonia has been guided by the principle that Moscow must be spoken to with a common voice for 15 years. In some cases, we have criticised our European allies when they rushed for close bilateral diplomatic ties with Russia that might damage solidarity in the European Union and NATO," he added.

In this context, President Kaljulaid's taking the initiative to arrange a direct meeting with Russian President Vladimir Putin deviates from Estonia's consistent foreign policy practice, Mr Terras argued.

He added that otherwise, there is essentially nothing extraordinary about the heads of two neighbouring states meeting.

"We have to take into consideration, however, that it is undoubtedly more favourable for Vladimir Putin if European states visit him one by one, and the frequency of these visits is rising gradually. We need to always be vigilant to avoid cutting off the branch we are sitting on," Mr Terras said.