Prime Minister John Key will talk up the Trans-Pacific Partnership when he's in Washington next week.
He's going there to attend the final round of leaders' talks on countering the threat of nuclear terrorism.
Mr Key has attended the three previous summits, which were held in Washington, Seoul and The Hague.
"Even as a small country New Zealand isn't immune from the risks posted by nuclear terrorism and it's important we play our part in efforts to prevent it," he said at his post-Cabinet press conference on Monday.
While he's in Washington Mr Key will meet senior members of President Barack Obama's cabinet for trade and economic talks. He'll also give a speech to the US Chamber of Commerce.
"During my visit I will set out the arguments in favour of the TPP," he said.
"My message will be that the agreement is good for the United States and the other 11 member countries, including of course New Zealand.
"It will set a new standard for trade and investment in one of the world's fastest-growing and most dynamic regions, creating jobs and boosting incomes."
The TPP is a political hot potato in the US, where it is strongly opposed by the Republican Party.
Republican presidential front-runner Donald Trump has said it's "a horrible deal" while Hillary Clinton, expected to secure the Democratic nomination, doesn't think it's good enough in its present form.
Mr Key will be in Washington from March 29 to April 1.