The United States has dispatched its top diplomat overseeing arm sales to promote U.S. weapons at the largest air show in Asia, where China's military footprint and political influence are seen to be surging.

Ambassador Tina Kaidanow told reporters that a large U.S. delegation at the Singapore Air Show is doing "everything we can" to encourage Southeast Asian governments to purchase U.S.-made arms like the F-35 fighter jet.

Washington has been seeking to woo countries like Vietnam, a former foe, with arms sales and transfers at a time when China has bolstered its territorial claims in the South China Sea with construction on man-made islands.

Kaidanow said the transfer last year of a coast guard cutter to Vietnam, which often contests China's maritime claims, was an "incredible positive."