Estonia called on its reservists to take part in the annual SIIL (Hedgehog-22) exercises on Tuesday alongside NATO forces.
The Estonian Ministry of Defence said 15,000 Estonian soldiers, including nearly 7,100 reservists and 4,200 allied soldiers will participate.
The Hedgehog drills are taking place in the south of the country - mostly near the border with Latvia - until June 3.
The drills took place as neighbouring Sweden and Finland overhauled decades-long foreign policy stances to apply for NATO membership in light of Russia's invasion of Ukraine.
Both countries joining would increase the security of the Baltic region, Estonian Foreign Minister Eva-Maria Liimets said on Monday (May 16).
She added Estonia appreciates NATO enforcing its presence in the Baltic region but would like the allies to move from enhancing their presence to enhancing their defense.
Finland and Sweden's formal applications mark one of the most significant changes in Europe's security architecture in decades, not least because Finland shares a 1,300-km (810-mile) border with Russia.
Switzerland, not an EU member state and long known for a neutral status that kept it out of two world wars, is also leaning more towards joining the defense alliance, the head of security policy at the Swiss defense ministry told Reuters earlier this month.
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