A Chinese politics specialist has called the deal between the Solomon Islands and China a "game-changer" saying New Zealand could be cut-off US military support.
A leaked draft of the agreement, which was verified by the Australian government, said Chinese warships would be permitted to dock on the islands and that Beijing could send security forces "to assist in maintaining social order".
The agreement is sparking concern China will look to throw its military weight around in the region.
"The broad nature of the security agreement leaves open the door for the deployment of Chinese military forces to the Solomon Islands," US State Department spokesman Ned Price said.
"We believe signing such an agreement could increase destabilisation within the Solomon Islands and will set a concerning precedent for the wider Pacific Island region."
New Zealand and Australia have made it clear they don't want China in our backyard.
"There is a lot of influence going on in the Pacific and there is a lot of pressure being placed on other Pacific countries around our region and what they need to understand is that I am going to work with them," Australian Prime Minister Scott Morrison said.
Ardern added: "We must draw clear lines where we have areas of concern and the militarisation of our region is a very clear line."
Solomon Islands Prime Minister Manasseh Sogavare said the pact would not "undermine peace and harmony" in the region.
Canterbury Univerisity Chinese politics specialist, Professor Anne-Marie Brady, told Rebecca Wright on Newshub at 8pm on Wednesday the Solomon Islands has no security threats to warrant this agreement.
"It has to be stressed as Prime Minister [Jacinda] Ardern has said and the Solomon Islands opposition leader has said, the Solomons does not have any external threats that would warrant this level of security presence from China in the Solomons."
Brady said that Solomon Islands and New Caledonia are strategically "extremely important" for China.
"Governments may change but geography does not, so these two small collections of islands in the Pacific guard very important shipping lanes that go from the north Pacific all the way down to Antarctica," she said.
Brady warned China could cut New Zealand and Australia off from US military support.
"If a hostile power has a base on these islands, they could blockade our wider Pacific seas as Japan attempted to do in World War 2," Brady told Newshub at 8pm.
"They could cut us off from military support from the United States or other countries who we partner with. They could also prevent New Zealand and Australia from going up into Asia or the Indo-Pacific region to defend and work with other partners."
Brady called the agreement a "game-changer" and said the New Zealand, Australian and US governments will be working extremely hard to come up with a solution to this deal.
"It's an absolute game-changer. As the Australian opposition foreign affairs spokesperson Penny Wong said in Parliament today [Wednesday] this is the biggest failing in Australian foreign policy history … It's really serious and our politicians know it, which is why they're speaking up so clearly."