'America First' turns US inward

The United States, under President Donald Trump's "America First" philosophy, slid into unilateralism in 2018 by imposing trade tariffs on steel and aluminum imports, including those from its allies, and intensifying trade frictions with China. During the year, it withdrew from the Iranian nuclear agreement signed in 2015 and threatened to do away with the Intermediate-Range Nuclear Forces Treaty it signed with the Soviet Union in 1957.

Trump insisted on a wall along the US-Mexico border to prevent immigrants from Central American countries entering the US. The budget required however has caused differences within the US political system, leading to a partial shut down of the government at the end of last year.