The query that we used to retrieve newspaper articles related to chemical weapons from the News section of Nexis Uni is shown below. This query has exactly the same structure as the query that we use daily to retrieve posts on chemical, biological, radiological, and nuclear (CBRN) weapons from Twitter. The HLEAD keyword was used to ensure that the searched words appeared in the title or the headline of the newspaper articles.

HLEAD ((chemical) AND (attack OR attacks OR bomb OR bombs OR missile OR missiles OR mortar or mortars OR rocket OR rockets OR weapon OR weapons OR security OR terror OR terrorism OR threat OR war OR wars OR warfare OR warhead OR warheads))

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