On April 13, 2018, Mattis briefed reporters in a press conference at the Pentagon on the 2018 missile strikes against Syria being carried out against the Assad regime's chemical weapon compounds, saying, "Tonight, France, the United Kingdom and the United States took decisive action to strike the Syrian chemical weapons infrastructure. Clearly the Assad regime did not get the message last year. This time our allies and we have struck harder. Together we have sent a clear message to Assad and his murderous lieutenants that they should not perpetrate another chemical weapons attack for which they will be held accountable".