Australia and Vanuatu signed a sweeping economic and security agreement on Monday that bars the establishment of any foreign military base in the Pacific nation. Vanuatu is at the centre of strategic rivalry between China and US allies in the South Pacific, and Australia has expressed concern that Beijing is seeking a permanent security presence in the region. The agreement commits Australia to $345 million in support for Vanuatu, whose largest external creditor is China, and it stops a foreign military power establishing a base there.