US military planes have been delivering humanitarian aid for Venezuela in the Colombian border town of Cucuta. The aid is being stockpiled at the request of the Venezuelan opposition leader, Juan Guaidó, who declared himself interim president last month. President Nicolás Maduro has alleged that the aid is part of a US plot to disguise an invasion into Venezuela. Mr Guaidó said some 600,000 Venezuelan volunteers would carry the aid across the border on 23 February.