The leaders of the 12 countries involved in the Trans-Pacific Partnership are sitting down together for the first time since an agreement was reached on the landmark free trade deal.
US President Barack Obama is hosting the meeting in Manila on the sidelines of the APEC summit.
"We were able to complete the negotiations thanks to the commitment of the leaders here," Mr Obama said at the beginning of the meeting.
"TPP is at the heart of our shared vision for the future of this dynamic region."
The TPP countries account for 40 percent of the world's GDP and a third of global trade.
Mr Obama called it the "highest standard and most progressive trade deal ever concluded", but acknowledged the negotiations were challenging.
"This is not easy to do, the politics of any trade agreement are difficult," he said.
Prime Minister John Key and Trade Minister Tim Groser are among those around the table.
Australian Prime Minister Malcolm Turnbull is seated next to Mr Obama.
The leaders will be discussing the next steps in the implementation of the TPP to ensure it is enacted as swiftly as possible.