SANTO ISLAND, Vanuatu — Australian officials have become increasingly concerned about China’s influence in the small island countries of the South Pacific, especially around infrastructure like a gleaming new wharf in Vanuatu that was built by a Chinese construction company and financed by the Chinese government.

The wharf, Australian officials said, could lead to China’s seizing strategic property and becoming a more direct military threat, within striking distance of Australia’s east coast.

But in a sign of the growing divide over China’s role, Vanuatu’s leaders are pushing back — sharing for the first time the contract this country signed with China for the wharf, and arguing they are perfectly capable of paying back the loans and making decisions on their own about when to work with China.

“The loan was considered economically viable for such infrastructure as the main gateway for international trade between the northern part of the country and the rest of the world,” said Foreign Minister Ralph Regenvanu of Vanuatu.