Archival content analysis studies of British and German newspapers and diplomatic documents in 1914 showed an increasingly asymmetrical pattern of perceived intentions. Levels of power motive imagery in reports or paraphrases of statements by the ‘other’ side were accentuated, while levels in reports or paraphrases of statements by one’s own (favored) side were diminished. As a result, the overall sense of threat was increased. In contrast, an archival study of US and Soviet newspapers during the peacefully resolved 1962 Cuban Missile Crisis showed no such pattern of asymmetrical accentuation-diminution. These results confirm a pattern of perceived intentions previously found in other escalating conflict situations, and are consistent with many related social psychological phenomena and experimental results. These findings suggest that comparing mutual perceptions of power imagery is a precise, operational way to measure ‘threatening’ intentions and thus an important mechanism of conflict escalation.