U.S. President Barack Obama met Thursday with the leaders of four African nations seen as poster-children for democracy and good governance, and pledged continued U.S. support for regional challenges such as terrorism and drug trafficking. President Obama held talks at the White House with Sierra Leone's President Ernest Bai Koroma, Senegalese President Macky Sall, Malawian President Joyce Banda and Cape Verde Prime Minister Jose Maria Pereira Neves. President Obama praised the leaders for overcoming challenges, including Sierra Leone's civil war and the recent constitutional crisis in Malawi, noting the leaders had discussed how to further strengthen democratic institutions and economic growth and mobilize young leaders. He said transnational threats of terrorism and drug cartels in West Africa undermine progress, but vowed "the United States will continue to cooperate with each of these countries to try to find smart solutions so that they can build additional capacity and make sure that these cancers don't grow in their region." The meeting comes as the continent faces growing challenges from conflicts in Mali and the Central African Republic, but President Obama did not address those conflicts in brief remarks to reporters following the talks.