Prices are subject to supply side shocks which can drive inflation up well above policy targets, as happened in 2011. Monetary policy cannot realistically prevent inflation from rising in the short term if prices have been hit by a large supply shock, such as a food price shock, in Uganda or anywhere else in the world.
Higher interest rates in the US or crises in other countries can bring about abrubt changes in financial conditions and trigger crises in emerging markets. But domestic policy management is very important as well. Recent studies, including one made at the Bank of Finland, show that excessive borrowing by the government or private banks seem to be key reasons for the recent crises.