The US military says 44 marines from Tonga have now arrived for duties in Iraq.
The contingent will patrol alongside US marines in the city of Ramadi, and other places north and west of Baghdad.
The headquarters battalion commanding officer, Colonel Stephen Baker says the first Marine Division welcomes the addition of the Tongan Royal Marines to their forces.
Tonga's military numbers about 4-hundred, and is engaged in the intervention force in Solomon Islands, and guarding the royal palace.
The force is mainly equipped with ageing Belgian assault rifles.