About 250 participants from Australia, Timor-Leste, Japan, New Zealand and the United States are taking part in 14 training activities across Timor-Leste.
In its 13th year, Exercise Hari'i Hamutuk - meaning 'build together' in the local Tetum - is strengthening readiness of soldiers in the region and deepening bonds.
Speaking at the opening ceremony, Australian Ambassador to Timor-Leste Caitlin Wells said it was fitting that the exercise started after the celebration of the 25th anniversary of INTERFET.
"This gives us [an] opportunity to reflect on just how far Timor-Leste, and your modern military force, have come in such a short time," Ms Wells said.
"Multilateral exercises such as these provide an opportunity for our military personnel to practise their core trades and learn from each other to improve their skills and build together."
At the heart of this year's training was the construction of two new barracks - for male and female soldiers - at Baucau Military Base.
The project involves engineers and tradespeople from the 1st Combat Engineer Regiment, 6th Engineer Support Regiment and School of Military Engineering, as well as engineers from Timor-Leste and the US Navy Seebees.
As the project neared completion, Officer Commanding Major Daniel Luhrs said he was proud of the collaborative effort.
"Many hands have truly made light work," Major Luhrs said.
"It's been incredible to see everyone surging in the same direction to get the job done.
"These new barracks will significantly enhance the living conditions for Timor-Leste's soldiers, especially as they look to accommodate more female personnel.
"This isn't just about physical construction; it's about building relationships. Every driven screw and every wall raised will leave a lasting legacy here at Baucau."
Teams from catering, signals, small-engines, combat engineers and medical trades also worked with Timorese soldiers, with an emphasis on practical training.
Lieutenant Sophie Hellemans, a nursing officer from the 1st Health Battalion, supported instruction in first aid and tactical combat casualty care.
"The soldiers we're teaching here are incredibly motivated," Lieutenant Hellemans said.
"Their enthusiasm for learning, alongside the exchange of knowledge between all our international partners, makes this training really collaborative.
"Our students started with an outstanding foundation, so we're refining skills and sharing knowledge, and all the Australian medical team are really improving their Tetum."
