Simplify the following text for a Grade 7 native English-speaking person.
Original: His disappearance was variously attributed to the failure of the industrialization scheme he had advocated while minister of industry , to pressure exerted on Castro by Soviet officials disapproving of Guevara 's pro-Chinese Communist stance on the Sino-Soviet split , and to serious differences between Guevara and the pragmatic Castro regarding Cuba 's economic development and ideological line . Pressed by international speculation regarding Guevara 's fate , Castro stated on June 16 , 1965 that the people would be informed when Guevara himself wished to let them know .
Simplified: Guevara joined Castro .