In all, over 13,000 soldiers from 13 countries are to take part in Siil 2018 ("Hedgehog 2018"), a defense exercise to be held in Southern Estonia in the first half of next May.

The two-week exercise, Estonia's largest yet, will begin on May 2, 2018, and take place across the entire country. The focus of the activity, however, will be on Viljandi, Tartu, Valga, Põlva and Võru Counties, military spokespeople told BNS on Thursday.

Altogether more than 13,000 members of the Estonian Defence Forces (EDF), Estonian Defence League (EDL) volunteers, reservists as well as allied and partner soldiers from 13 countries are expected to participate in the exercise.

In the course of the exercise, the combat readiness of EDF units will be evaluated and the performance of combat tasks and cooperation between the EDL and EDF units will be rehearsed.

Commander of the Estonian Defence Forces Gen. Riho Terras said that at next year's Siil exercise, a large portion of reservists and volunteers will rehearse the performance of tasks related to territorial defense.

"Territorial defense is the security blanket whose toughness and resilience our defense capability depends upon," Terras said.

The training exercise will be divided into three phases: a combat readiness phase lasting until May 4; an interoperability training and mortar and antitank live-fire exercise phase from May 5-7; and a phase of training battles from May 8-12. During the latter, the 2nd Infantry Brigade in conjunction with units from Germany, Finland, Latvia, Lithuania and the United States will rehearse action against mock enemy forces made up of the 1st Infantry Brigade and the NATO Battle Group stationed in Estonia.

More than 13,000 reservists, EDL volunteers, conscripts, active service personnel and allied soldiers took part in the previous Siil exercise in May 2015, where reservists made up more than half of the participating personnel.

The purpose of the 2015 exercise was to check the performance of various units and branches of the military in augmenting units that are in permanent readiness and the formation of units in rapid response readiness, as well as to rehearse combat by the 1st Infantry Brigade and tactical and operational command.