The dollar firmed on Monday as traders pondered the ramifications of U.S. President Donald Trump's tariff plans at the start of a week in which the Federal Reserve is widely expected to hold interest rates steady.

The dollar began the week with modest gains after a brief threat of US tariffs on Colombia made clear the trade risk that still hangs over the currency market.

The U.S. dollar weakened on President Donald Trump’s Inauguration Day, and remained under pressure Tuesday after it became clear immediate tariffs weren’t in the cards, according to BofA Global Research.