Republican US presidential candidate Ben Carson has endorsed US statehood for Puerto Rico, citing its “very strategic” location for military defence, and raised concern about Chinese “infiltrating” the Caribbean. Speaking at a convention for Puerto Rican gubernatorial candidate Ricardo Rossello, a member of the island's pro-statehood party, Carson said on Sunday he “would be incredibly honoured and delighted for Puerto Rico to be the 51st state.” “One thing I've found when I have come to Puerto Rico is extremely friendly people,” the 64-year-old retired neurosurgeon said, adding that “we have probably more patriotic Puerto Ricans than almost any other state.” Statehood is a central political issue in Puerto Rico, a US territory whose two main parties are the pro-statehood PNP and pro-commonwealth PPD, each of which have Democrats and Republicans within their ranks. The island's fate has also made it onto US presidential candidates' agendas because Puerto Ricans can vote in presidential primaries - though not general elections - and because Florida, a key swing state, is home to nearly 1 million Puerto Ricans. Carson has found little support among Republicans in Puerto Rico, who mostly favour candidates Jeb Bush and Marco Rubio, both of whom have endorsed statehood for the U.S. commonwealth. Carson called Puerto Rico “very strategically located for the defence of America, right near Cuba.” “We have the Chinese already coming in and infiltrating the Caribbean,” he said. “We also have to recognise that we have global jihadists who are trying to destroy us. We need unity.” Carson, neck and neck with Donald Trump atop Republican polls, spoke for about five minutes without addressing recent headline-grabbing allegations that he misrepresented facts surrounding a scholarship offer to the US Military Academy at West Point, and fabricated details of a violent exchange with a friend as a child. Those supporting statehood reason that inclusion for Puerto Rico in the US would provide equal treatment on issues like federal Medicaid and Medicare reimbursements, while those against are wary of risking the island's independence and cultural identity. With Puerto Rico facing a US$72 billion debt load and a roughly 45 per cent poverty rate, Governor Alejandro Garcia Padilla of the pro-commonwealth Popular Democratic Party, faces historically low approval ratings and strong challenges in next year's election from statehood candidates such as Rossello and Puerto Rico Resident Commissioner Pedro Pierluisi.