RIO DE JANEIRO (Reuters) - U.S. government officials in March asked Brazil's state-run oil company Petrobras whether it could increase crude output after Russia's invasion of Ukraine sent global prices soaring, three people with knowledge of the matter told Reuters. They came away empty-handed, the sources said. Officials at Petrobras, formally Petroleo Brasileiro SA, said output levels were a function of business strategy rather than diplomacy and also that a significant short-term production boost would not be logistically possible, the sources said. "We are ... doing everything possible with our allies and partners to mitigate the economic impacts of Russian...