US Defense Secretary Lloyd Austin announced on Thursday the deployment of a US Coastguard ship to Papua New Guinea (PNG), as Washington seeks to boost its military footprint in the region amid fierce competition for influence with China.

"A US Coastguard cutter will be here in August," Austin confirmed, as he became the first Pentagon chief to visit Papua New Guinea.

The move capitalizes on a recently signed security pact between the two countries that offers the United States greater military access to a strategically important part of the South Pacific.

Austin indicated that the coastguard deployment would help Papua New Guinea stop the plundering of its thinly protected maritime resources, stopping activities like illegal fishing and trafficking.

According to a landmark US-Papua New Guinea security pact signed earlier this year, the United States will be able to develop and operate out of facilities across the country.

With Papua New Guinea's agreement, the US military can station troops and vessels at six key ports and airports, including Lombrum Naval Base on Manus Island and facilities in the capital Port Moresby.

Washington would have "unimpeded access" to the sites to "pre-position equipment, supplies and materiel" and have "exclusive use" of some zones where development and "construction activities" could be carried out, according to the text.

Nevertheless, Austin attempted to cushion concerns that the pact would erode the South Pacific nation's sovereignty and independence.

"I just want to be clear that we're not seeking permanent basing in PNG," Austin claimed, adding that "this is an opportunity to expand upon a long-standing relationship."

Prime Minister James Marape also alleged that the pact would help modernize Papua New Guinea's infrastructure and strengthen its security.

"They have never tampered with our sovereignty and our autonomy and our independence," Marape claimed.

"It is not them coming in. We invited them in... to build up our defence to protect our own borders, including stopping the theft of fish from our seas," he added.

"We're doing this for the betterment of our country."

Marape indicated that the "USA do not need PNG's ground to be a launching platform for any offensive anywhere else in the world" as the US has bases in the Philippines and South Korea, which are "much closer to China than PNG."

He noted that PNG has a "specific economic relationship" with China, claiming that through its embassy in PNG, the Chinese government has relayed to Port Moresby that they had "no issue whatsoever with us signing the DCA with the USA."

Elsewhere, he said PNG "will not compromise our relations with China and other nations" by expanding security cooperation with the US.

Read more: US troops deployment doc. out; PNG sovereignty called into question