Prinsip perdagangan bebas selalu menjadi fokus utama dalam kegiatan ekonomi Amerik Serikat, tetapi pada rentan waktu 2017–2021 pada periode pemerintahan Presiden Trump ada yang tidak biasa dari kebijakan ekonomi Amerika Serikat yang cenderung proteksionis. Langkah proteksionisme lahir atas beberapa indikator yang menjadi bahan pertimbangan dan indikator tersebut berorientasi pada kepentingan dinamika politik domestik dan dinamika ekonomi domestik Amerika Serikat. Penelitian ini dilaksanakan untuk mengungkapkan faktor-faktor penentu utama langkah Amerika Serikat dalam menerapkan proteksionisme serta dampak yang harus dihadapi Amerika Serikat. Teori Realisme Neoklasik, serta konsep-konsep seperti proteksionisme, Kepentingan Nasional, Proses Pengambilan Keputusan politik akan dijadikan landasan berpikir. Penelitian menggunakan pendekatan kualitatif dengan menggunakan metode penelitian deskriptif. Data dikumpulkan melalui sumber sekunder dan dianalisis dengan metode historis. Hasil penelitian menemukan bahwa tekanan politik dari para konstituen Presiden Trump merupakan bagian dari dinamika politik domestik, baik dari kalangan masyarakat maupun para aktivis partai yang juga para elit ekonomi industri manufaktur. Penurunan kapasitas ekonomi domestik dengan tolak ukur defisit neraca perdagangan, penurunan angka PDB dan angka pengangguran merupakan bagian dari dinamika ekonomi domestik. Berdasarkan aspek tersebut dapat disimpulkan bahwa langkah untuk menetapkan proteksionisme merupakan keputusan yang diambil oleh pemerintahan Presiden Trump berdasarkan pengaruh dari dinamika politik dan ekonomi domestik dengan tujuan untuk menjawab masalah yang tengah dihadapi dan demi mengembalikan Amerika Serikat pada masa kejayaanya. / The principle of free trade has always been the focus in the economic activities of the United States, but in the period 2017–2021 during the Trump administration period, there is something unusual about the United States' economic policy that tends to be protectionist. The Protectionism measure was born out of several indicators that were taken into consideration, and these indicators were oriented to the interests of the dynamics of domestic politics and the dynamics of the United States' domestic economy. This research was conducted to reveal the main determinants of the United States' steps in implementing Protectionism and the impact that the United States had to face. Neoclassical Realism theory, as well as concepts such as Protectionism, National Interest, Political Decision-Making Processes, will be used as the basis for the research. The research used a qualitative approach and utilizing descriptive research methods. Data will be collected through secondary sources and will be analyzed using historical methods. The results of the research found that political pressure from President Trump's constituents is part of the dynamics of domestic politics, both from his voters and party activists who are also the economic elite of the manufacturing industry. The decline in domestic economic capacity by measuring the trade deficit, decreasing GDP, and unemployment is part of the dynamics of the domestic economy. Based on these aspects, the research concluded that the Protectionism step to establish a Protectionist measure is a decision taken by the Trump administration based on the influence of domestic political and economic dynamics to restore the United States to its former glory. The research concluded that Protectionism was a decision taken by the Trump administration based on the influence of domestic political and economic dynamics to solve the problems currently being faced and to restore the United States to its former glory.