On Wednesday, President Donald Trump announced the US was imposing reciprocal tariffs on a small collection of Antarctic islands that are not inhabited by humans, as part of a global trade war aimed at asserting US dominance. The Heard and McDonald Islands, known for their populations of penguins and seabirds, can only be reached by sea.

Trump announced the countries now subject to tariffs in a Wednesday press conference, using a poster as a prop. Additional countries—including the Heard and McDonald Islands, which are, incidentally, not countries—were listed on sheets of paper distributed to reporters.

One of the sheets claims that the Heard and McDonald Islands currently charge a “Tariff to the U.S.A.” of 10 percent, clarifying in tiny letters that this includes "currency manipulation and trade barriers." In return, the sheet says that the US will charge "discounted reciprocal tariffs" on the islands at a rate of 10 percent.

The islands are small. Their reported 37,000 hectares of land makes them a little larger than Philadelphia. According to UNESCO, which designated the islands as a World Heritage Site in 1997, they are covered in rocks and glaciers. Heard Island is the site of an active volcano, and McDonald Island is surrounded by several smaller rocky islands. The islands are home to large populations of penguins and elephant seals.