Armed conflicts and attacks
- Somali Civil War (2009–present)
- Twenty-eight people are killed in a coordinated attack on the Dayah Hotel in central Mogadishu. The terrorist group Al-Shabaab claims responsibility. (Yahoo!) (Al Jazeera)
Business and economy
- The Dow Jones Industrial Average breaks 20,000 for the first time ever. (CNBC)
Disasters and accidents
- Over 800 homes are destroyed or flooded in Tahiti, French Polynesia, following severe storms over the weekend, with at least 4,000 people affected. (Radio New Zealand)
International relations
- 2017 Mexico–United States diplomatic crisis
- Mexican President Enrique Peña Nieto rejects the idea, announced by U.S. President Donald Trump, that Mexico would pay for any border wall between the United States and his country. (The Telegraph) (NBC news)
- Mexican senior officials say President Peña Nieto may cancel his plans to visit the White House next Tuesday, January 31, because of President Trump's actions. (The New York Times) (Fortune)
- Foreign relations of Taiwan
- Burkina Faso and Swaziland refuse to break relations with Taiwan and recognize the One-China policy despite being offered aid from China. (Bloomberg)
Law and crime
- The German government decides it will abolish the crime of lèse-majesté, almost one year after the Böhmermann affair. (AFP by Digital Journal)
- Domestic violence
- Women's rights
- Belgium supports a plan by Dutch minister Lilianne Ploumen to launch a fund compensating worldwide for the United States' newly-reinstated Mexico City policy. (De Standaard) (Reuters)
Politics and elections
- The Vatican City State announces that Pope Francis will name a Pontifical Delegate to head the Sovereign Military Order of Malta after Prince and Grand Master Matthew Festing's unexpected forced resignation in a spat over condoms. (Reuters)
- Presidency of Donald Trump
- United States President Donald Trump announces that he intends to seek an investigation into possible voter fraud from last year's election. (Reuters) (FOX News)
- President Trump signs two executive orders related to immigration, one to take federal grant funding away from sanctuary cities, and another to build a wall along the U.S.–Mexico border. (CNN)
Sports
- The International Olympic Committee says that sprinter Nesta Carter took the banned substance methylhexaneamine while competing in the 2008 Olympic 4 × 100 metres relay. As a result, the Jamaican team is disqualified and Usain Bolt loses his ninth Olympic gold medal. (ESPN)
- With a victory in the second stage of the Vuelta a San Juan, Tom Boonen becomes the first professional road cyclist to win a race on a bike equipped with disc brakes. (RoadCyclingUK)
- In sumo wrestling, Kisenosato Yutaka becomes the 72nd yokozuna. He is the first Japanese national to effect the promotion to the highest rank in 19 years. (Time)