During Donald Trump's first administration (January 20, 2017 – January 20, 2021), the United States was involved in several ongoing military conflicts and operations, though no major new wars were initiated. The primary engagements were as follows:

1. War in Afghanistan

The U.S. continued its involvement in the war in Afghanistan, the longest-running conflict in American history. Trump oversaw a policy shift, including increasing troop levels early in his term and later negotiating a peace agreement with the Taliban in February 2020. The agreement outlined a U.S. withdrawal plan, contingent on Taliban adherence to certain conditions.

2. Operations in Iraq and Syria

The U.S. remained active in the fight against ISIS (the Islamic State). Under Trump, the military intensified its efforts, and by 2019, ISIS had lost its territorial "caliphate." The administration also conducted operations to eliminate ISIS leaders, such as the killing of Abu Bakr al-Baghdadi in October 2019.

In Syria, U.S. forces also clashed with pro-Syrian government militias in some instances.

3. Yemen Civil War

While the U.S. was not directly at war in Yemen, it supported Saudi Arabia's military campaign against the Houthi rebels. This involvement included arms sales and intelligence support, which faced significant criticism due to the humanitarian crisis in Yemen.

4. Drone Strikes and Counterterrorism Operations

The Trump administration expanded the use of drone strikes and special operations missions in countries like Somalia, Yemen, Pakistan, and Libya as part of broader counterterrorism efforts.

5. Tensions with Iran

U.S.-Iran relations became particularly fraught under Trump. In January 2020, the U.S. carried out a drone strike that killed Iranian General Qasem Soleimani in Iraq, escalating tensions. This led to Iranian missile strikes on U.S. bases in Iraq, marking a near-war crisis, though full-scale conflict was avoided.

While no large-scale new wars were declared, these conflicts and operations underscore the U.S.'s continued military engagement during the Trump administration.