New Zealand Prime Minister Jacinda Ardern says including the US in the Trans-Pacific Partnership would not be a simple process.

This follows President Trump's announcement the US may rejoin the landmark agreement. Ardern said Washington's return to the fold would not be a straightforward matter of slotting the country into the deal. Trump has said the US would rejoin the TPP if it offered what he described as "substantially better" terms. The TPP was designed to take down trade barriers in the Asia-Pacific region. Trump pulled the US out of the pact in early 2017, citing concerns about US jobs.