Tonga's Director of Tourism says the decision to pull out of the Tonga-Samoa-Los Angeles Air New Zealand service was a very difficult one.
The last flight on the route will be at the end of January, ending an arrangement that also involved a New Zealand government contribution.
Samoa's Minister of Tourism, Misa Telefoni, says Tonga's decision to pull out was a key factor that resulted in the service being terminated.
But Tonga's Tourism Director, Sakopo Lolohea, says it had no choice.
"One of the main things we considered is actually the cost of operating this flight and we had long discussions but we haven't had an alternative on how to cut down the cost to make it viable."
Mr Lolohea says they are looking at other options.