Determining whether the opposition is benign or malign is central to the security dilemma. In this context, states have to decide whether the military capabilities of others are for defensive or offensive purposes. Despite the importance of this issue, states’ use of intelligence and diplomacy to gauge others’ capabilities and intentions and its implications for exacerbating, ameliorating and escaping the security dilemma have hardly been addressed. The few who have engaged with the topic have only done so superficially. This article engages with the subject matter at length and argues that both intelligence and diplomacy are double-edged swords in the security dilemma. Intelligence is particularly useful in attaining information regarding the capabilities of others and diplomacy is of great value in acquiring information about their intentions. Yet, they are both prone to error. The best prospects of mitigating and escaping the security dilemma are therefore by utilizing intelligence to gauge others’ capabilities and diplomacy to decipher their intentions, even though these efforts may instead end up aggravating the security dilemma dynamics due to mistakes.