U.S. President Barack Obama landed in Cuba on Sunday, beginning a round of official meetings today on issues that could immediately advance U.S. interests in Latin America. Obama and Cuban President Raul Castro will lay the groundwork for further economic transactions by loosening U.S. restraints on trade with Cuba. But amid overwhelming coverage of the president's much-publicized trip to Cuba, the strategic significance of the island nation to the United States has been blatantly absent. That is because Cuba has enduring importance to long-term U.S. security, which in the current lull of direct threats to the U.S. mainland has enabled less strategically important issues to take precedence....