One of the highest-ranking US officials in the Pacific has refused to rule out military action against the Solomon Islands if it allows China to create an army post there, claiming that the nations' security agreement had "potential regional security implications" for the US and other allies.

Ambassador Daniel Kritenbrink, assistant secretary of state for East Asian and Pacific Affairs, traveled to the Pacific country last week as part of a high-level US team.

He said the US delegation, including Kurt Campbell, the National Security Council's coordinator for Indo-Pacific affairs, had a 90-minute "constructive and candid" meeting with Prime Minister Manasseh Sogavare. The US delegation expressed concerns about China's recently signed security deal.

"We wanted to communicate our concerns to our Solomons friends," Kritenbrink explained. "Prime Minister Sogavare noted that the Solomon Islands believe the deal they reached is entirely domestic in nature. However, we have made it clear that the pact may have regional security ramifications, not only for us, but for allies and partners throughout the region."

On Tuesday, Kritenbrink reaffirmed the US's willingness to intervene in the region if China establishes a military post.

"Of course, we respect the Solomon Islands' sovereignty, but we also wanted to communicate to them that if steps were taken to establish a de facto permanent military presence, power projection capabilities, or a military installation, we would have serious concerns and would respond very naturally," he said.

When asked what that response may entail, he stated, "Look, I'm not going to speculate and I'm not in a position to discuss what the US might or might not do in such a situation."

When asked whether he would rule out the possibility of the US taking military action against the Solomon Islands in the event of a naval base being established and, if not, whether he agreed with Australian Prime Minister Scott Morrison's assertion that the base would be a "red line" for Australia, he responded: "I don't have much to add beyond what I've already stated."

Last week, the Biden administration stated that the US would "respond appropriately" if China was permitted to maintain a long-term presence on the islands, despite Sogavare's assurances that he had no intention of authorizing a military station.

Following the statement, Australia's prime minister, Scott Morrison, declared that Australia shared the US's "red line" on China's involvement in the Solomon Islands. In his Anzac Day address on Monday, Defense Minister Peter Dutton said that "Australia should prepare for war," claiming that China was "on a very deliberate course at the moment."

Kritenbrink also addressed China's military ambitions, saying, "I believe it is critical in this context to remember that the PRC [People's Republic of China] is attempting to establish a more robust overseas logistics and basic infrastructure that would enable the PLA [People's Liberation Army] to project and sustain military power over greater distances. As a result, we desired to have an open discussion with our Solomons friends. We articulated our concerns... and we've signaled that we would continue to closely monitor the situation and communicate with them in the future."

The security agreement between China and the Solomon Islands remains secret, despite calls from Solomon Islands lawmakers for the prime minister to make it public.

"I believe it is obvious that this agreement was observed by only a few people in a very restricted group. And the prime minister has publicly stated that he would release specifics only with China's approval, which I believe is another cause for concern," said Kritenbrink.

However, a draft of the agreement was released on social media last month. It included provisions authorizing China to "make ship visits, carry out logistical replenishment, and have stopover and transition in the Solomon Islands."

"The United States of America is not in the business of compelling countries to choose between the United States and China or anyone else," Kritenbrink stated. However, it is interested in supporting "a proactive vision for reinstating the shared interests and principles that we believe are critical for all of our regional friends."