U.S. Homeland Security Secretary Kirstjen Nielsen is asking Central American nations to do more to stop migrant caravans and fight transnational crime.

Nielsen says the region is facing a humanitarian and security crisis. She calls on security ministers from El Salvador, Guatemala and Honduras "to show a bold leadership to stop the formation of new caravans."

Nielsen spoke Wednesday in El Salvador's capital during an encounter with Central American counterparts to discuss a regional security plan to fight illegal human trafficking, organized crime and gangs, and expand intelligence sharing and fortify border security.

In recent months thousands of Central Americans have moved in caravans toward the U.S. border. Those in the caravans repeatedly say they are fleeing violence and poverty and hope to apply for refuge in the United States.