WASHINGTON -- The commanders of U.S. Africa Command and U.S. Southern Command shared the challenges their commands face with lawmakers on Capitol Hill.Army Gen. Stephen J. Townsend, Africom's commander, and Navy Adm. Craig S. Faller, the Southcom commander, appeared before a Senate Armed Services Committee hearing Thursday on the fiscal year 2021 defense funding request and the Future Years Defense program.Africa is a global crossroads with strategic choke points and sea lines of commerce that are critical to U.S. operations in the world, Townsend told the Senate panel. Future U.S. security and prosperity rest on access to this strategic asset in times of crisis and ensuring these waters remain free, open and secure, he said. Africom is engaged in an ongoing, blank-slate review in concert with the Defense Department, he noted."We've developed a prioritized list of objectives and actions to protect the homeland and secure our strategic interests in Africa while ensuring the American taxpayers' investments are in the right areas," the Africom commander said.Africa is key terrain for competition with China and Russia, which are aggressively using economic and military means to expand their access and influence, Townsend said. "I believe Africa offers America a competitive edge over China and Russia, and we should take advantage of it," he added.Townsend said Africom will grow more efficient to contribute to higher defense priorities and refocus resources to global power competition, but cannot take pressure off major terrorist groups such as al-Qaida and ISIS, adding that such groups and others remain an "inconvenient reality" in Africa."While we should not try to confront each one, we should remain resolute in confronting those who threaten Americans and the American homeland, like al-Shabab -- the largest, most violent of al-Qaida's branches," Townsend said. "Today, Africa does that with a light and relatively low-cost footprint by supporting African and international partners who are leading these efforts."The Africom commander said a "few troops and a few bucks" can go a long way and make a real difference in Africa. Africom's whole-of-government and partner-centric approach acts as a force multiplier to address Africa's many complex challenges, he added."What Africom accomplishes with a few people and a few dollars on a continent three and a half times the size of the continental United States is a bargain for the American taxpayer and low-cost insurance for America in that region," Townsend said. "A secure and stable Africa remains an enduring American interest. U.S. Africom stands ready to protect and advance American interests and respond to crises in Africa."Faller noted that for the United States and the countries in Southcom's region, the Western Hemisphere is "our shared home.""It's our neighborhood," he told the committee. "We're connected to the nations there in every domain -- sea, air, space, land, cyber and, most importantly, culturally and with values."Over the last year, the admiral said, he has visited partners and seen first-hand the opportunities and challenges that directly affect Western Hemisphere security. "I've come to describe the challenges of as a vicious circle of threats that deliberately erodes the security and stability of this region in the United States of America," he told the senators.This vicious circle is framed by the systemic issues of young democracies with weak institutions and rampant corruption, he noted. Exploited by transnational criminal organizations that are often better funded than the security organizations, he said, they face external state actors that don't share democratic values. China, Russia, Iran and violent extremist organizations are trying to advance their interests at the expense of U.S. and partner-nation security, Faller said.