The world’s largest humanitarian crisis is unfolding in Yemen. Some 5,000 civilians have been killed, many of them from airstrikes by a Saudi-led coalition intervening in Yemen’s civil war. The country faces the fastest growing cholera epidemic ever recorded. Over 18 million people in the country are in need of humanitarian assistance, with millions of them at risk of famine.

The United States is one of the only countries that can change the trajectory of the conflict. It should withhold intelligence and military support to the Saudi-led coalition and require it to abide by international law and stop targeting civilians. In doing so, the United States can improve the humanitarian situation in Yemen and help bring an end to the fighting.

The United States has supported the Saudi-led coalition since 2015 with military assistance and intelligence in the fight against Houthi rebels in Yemen’s civil war. However, the fighting has displaced millions of Yemenis. Airstrikes by the coalition have resulted in significant civilian casualties and widespread infrastructure damage.

The Saudi-led coalition has also greatly impeded relief for the Yemeni people. The coalition’s air and sea blockades have deepened the humanitarian crisis and made it hard for the United Nations and other organizations to deliver aid to Yemen. The coalition has also blocked commercial goods shipments, devastating Yemeni markets and pushing more people into turmoil and hunger.

Notably, the coalition’s blockade has impeded U.S. efforts to respond to the crisis. Earlier this year, the U.S. sponsored cranes through the World Food Programme to replace ones destroyed in 2015 due to airstrikes. The cranes were to be sent to the Yemeni port Hodeidah, which would greatly improve unloading of humanitarian and commercial cargo in one of the densely-populated areas of Yemen. However, the Saudi-led coalition has not let the cranes reach the port.

Policy needs to change now. By withholding its support for aggressive action by the coalition, the United States will signal that it does not condone escalation of the crisis. The U.S. can then address the problem, step back from a negative role, and step into a positive one.

A change in policy enhances U.S. security. Instability in Yemen contributes to extremism. The fighting in Yemen has strengthened al-Qaeda in the Arabian Peninsula. Harsh conditions can lead some, particularly youth, to turn to extremists who promise them survival. The U.S. will improve homeland security by working to de-escalate the conflict.

A change in policy gives the U.S. leverage to improve the humanitarian response. The loss of significant military support will put enormous pressure on the coalition to lift the blockade and allow aid and commercial goods distribution.

The United States should not applaud small steps, but demand big ones. In exchange, the U.S. would be able to provide the coalition support aimed at facilitating a peaceful resolution of the conflict. In fact, a renewed U.S. focus on resolution of the conflict in Yemen underscores the importance of regional stability and Saudi Arabia’s security.

The images of destruction and famine in Yemen are not ones the U.S. should tolerate. The United States should refocus its strategy in Yemen from supporting arms to supporting peace. The United States has the power to improve the lives of over 18 million people who are suffering. Now is the time to act.