The Russians and the Chinese were increasingly fed up with North Korea’s failure to repay loans that had amounted to an estimated $10 billion by the early 1990s. Moscow decided that North Korea would have to pay prevailing world prices for Soviet imports rather than the lower “friendship” prices charged Communist allies. In the past, the Chinese, who provided three quarters of North Korea’s fuel and two thirds of its food imports, used to say they were close as “lips and teeth” to North Korea; now they wanted cash up front.