The Estonian Defense Forces' (EDF) ESTCOY-18 company took over the rotating duties of the US-led mission Operation Inherent Resolve in Iraq this week, replacing the Netherlands.
ESTCOY-18, a Scout Battalion's reduced infantry company, is based at the International Joint Task Force at Erbil Air Base.
The unit will be responsible for base protection, rapid response and providing security for key personnel.
The Dutch, which has a similar size company, handed over their responsibilities to the Estonians on Monday with a flag-raising and lowering ceremony.
"Serving here requires constant attention and discipline, which can be a challenge in the apparent quiet. I wish the Estonians the very best in their service, and I have no doubt that you will succeed in your tasks," said Dutch Company Commander Captain Jeffrey.
The Estonian unit will hand over its duties to the next rotation in October.
Operation Inherent Resolve works by, with and through regional partners to militarily defeat the Islamic State of Iraq and Syris (ISIS), to increase regional stability, the U.S. Department of Defense says.
Estonia has sent troops to Iraq in various missions since 2003.
Editor: Merili Nael, Helen Wright