He withdrew from major climate and trade agreements, banned travel from seven Muslim-majority countries, issued other tough immigration restrictions, launched a trade war with China, implemented record tax cuts, and reshaped Middle Eastern relations.
For nearly two years, a special counsel probed alleged collusion between the 2016 Trump campaign and Russia. Thirty-four people faced criminal charges – on matters such as computer hacking and financial crimes – but not Trump. The investigation did not establish criminal collusion.
Soon after, Trump became just the third US president in history to be impeached, over accusations he pressured a foreign government to dig up dirt on Democratic rival Joe Biden. He was impeached by a Democrat-led House of Representatives but acquitted in a Republican-led Senate.
His 2020 election year was dominated by the coronavirus pandemic.
He faced intense criticism for his handling of the crisis as the US led the globe in deaths and infections and for controversial comments, like suggesting research into whether the virus might be treated by injecting disinfectant into the body.
He was forced to take a break from the campaign trail in October after he was diagnosed with Covid-19 himself.