Many scientists have described the anthropogenic climate changes as one of the most pervasive threat of our time that will form this and future generations. Despite that is the climate change is still controversial and missing from the American security agenda. The purpose of this study is to empirically analyse the American environmental discourse under the administration of Donald Trump and the omission of climate changes in the security agenda. To be able to explain the absence of the climate changes in the American security agenda, the environmental discourse will be analysed and the theoretical framework of Copenhagen’s school of securitization will be used to define the current description of the environment, the climate threats, and the global warming. By using a qualitative text analysis, consisting of a discourse analysis, lectures, debates, and documents from the Trump administration are examined, to be able to understand how the discourse is constructed and thus how the omission of the climate changes from the security agenda can be understood by using the securitization theory. The study indicates that the approach taken by the Trump administration on the American environmental discourse is produced can prevent the climate changes, the global warming, and the environment to be securitized, which in its turn can contribute to understanding of why it has not been brought up in the American security agenda. In the analysis it can be concluded that the Trump administration have moved towards a morepoliticized discourse, but also towards a depoliticized discourse.