Lateral pressure is a relatively neutral concept similar to what Pitirim Sorokin (1957: 565) called economic expansion and Simon Kuznets (1966, 334-348) referred to more broadly as outward expansion. The strength of a country's lateral pressure is generally taken to correlate positively with its "power" as conventionally understood. The theory of lateral pressure draws on the level of analysis or Image perspective in international relations (Boulding 1956; Waltz (1979) largely as an initial framing and extends this traditional perspective in specific ways.