The likely assassination of the Saudi critic and Washington Post journalist Jamal Khashoggi underscores how urgent it has become for the United States to redefine our relationship with Saudi Arabia, and to show that the Saudis do not have a blank check to continue violating human rights.

One place we can start is by ending United States support for the war in Yemen. Not only has this war created a humanitarian disaster in one of the world’s poorest countries, but also American involvement in this war has not been authorized by Congress and is therefore unconstitutional.

In March 2015, a coalition of Arab states led by Saudi Arabia and the United Arab Emirates started a war against Yemen’s Houthi rebels. Since then, many thousands of civilians have been killed and many more have lost their homes. Millions are now at the risk of the most severe famine in more than 100 years, according to the United Nations. The chaos in Yemen has also provided fertile ground for extremist groups like Al Qaeda and the Islamic State, and created new opportunities for intervention by Iran.

The United States is deeply engaged in this war. We are providing bombs the Saudi-led coalition is using, we are refueling their planes before they drop those bombs, and we are assisting with intelligence.