Watch: Marshall Islands journalist says Trump's USAID freeze ...

Marshall Islands Journal owner and publisher Giff Johnson says Trump's decision "is an opening for anybody else who wants to fill the gap".

Trump froze all USAID for 90 days on his first day in office and is now looking to significantly reduce the size of the multi-billion dollar agency.

The Pacific is the world's most aid dependent region, and Terence Wood from the Australian National University Development Policy Centre told RNZ this move would hit hard.

"The US is the Pacific's largest aid donor and what is happening there is completely unprecedented ... there's also a cruel irony that Elon Musk is the world's wealthiest man and right now he seems to be calling the shots with decisions that are literally going to be life or death for the world's poorest people ... it's hard to wrap one's head around," he said.

Wood was concerned about how the dismantling of US AID would impact the Pacific.

"It's not a good time to be in the world's most aid dependent region ... indeed Sāmoa PM Fiame Naomi Mata'afa has already expressed concern about what might happen to funding for organisations like World Health Organisation ... so everyone is watching this with considerable alarm."

'It's hard to believe that Trump has changed his sense'

A senior publisher and journalist in Micronesia told RNZ Trump's shutdown of USAID was at odds with the increased engagement in the Pacific.

Johnson said the move did not line up with the president's rhetoric on China, and the fact the new US compact agreements were instigated by his administration the last time he was in power.

"So it's hard to believe that Trump has changed his sense and I mean, he's putting tariffs in on China, right?... So that's still very much in play," Johnson said.

"It's just like amazing to me that that they're willing to undermine relationships in the Pacific that they claim to be a very important region for them.

"And you know, this is, I mean, certainly it's an opening for anybody else who wants to fill the gap, I suppose, until Washington decides what it is doing."

Meanwhile in the Cook Islands, the vice chairperson of the Pacific energy regulators Alliance said Trump's shutdown of US Aid was a big deal for the region.

Dean Yarrall said his organisation was planning a multi-day training course on best practices in electricity regulation, funded by the US, which had now been called off.

He said the cancelling of the training course caught his organisation off guard.

"We're seeing a lot of competition between parties, the Chinese are looking to increase the influence Australia as well and the US through USAID are big supporters of the Pacific so seeing USA sort of drop away, I think that'll be there will be a big thing," Yarrall said.