Venezuela’s national oil company is being shaken by claims of corruption and by internal dissent, indicating fissures within the institution largely responsible for financing President Hugo Chávez’s widening array of social welfare programs and foreign aid projects.

As the world warms, water -- either too little or too much of it -- is going to be the major problem for the United States, scientists and military experts said Monday. It will be a domestic problem, with states clashing over controls of rivers, and a national security problem as water shortages and floods worsen conflicts and terrorism elsewhere in the world, they said.