Kaljulaid is visiting the exercise on Saturday to get an overview of the exercise and meet with members of the defense forces attending it.

According to Kaljulaid, in the present security situation it has to be possible to mobilize the Estonian reserve army in a matter of hours and days. "Quickly carrying out mobilization can't be practiced only on paper and at field exercises, but also by calling on reservists to take arms in a short amount of time, if necessary. Therefore such snap exercises will transition from a surprising and unusual phenomenon to a familiar routine," she added.

"I thank and recognize all reservists who showed up, but also the ones who dutifully said they can't come, for fast reaction and their will to defend. And their next of kin and employers for their understanding and patience," the head of state said.

The Estonian government decided at an extraordinary meeting on Wednesday to hold an emergency military exercise involving 669 reservists beginning Thursday. More than 500 reservists showed up for the snap exercise which is to last until Sunday evening.

This is the second time that Estonia is testing its actual defense capability in such a way. In the first similar snap defense readiness exercise held in December 2016, more than 300 reservists and Kaitseliit volunteers were called up in North and South Estonia.