French train attack hero Spencer Stone was in a critical condition after being stabbed on Wednesday night.
The senators said in the letter that "the American people are heartbroken and outraged," after last week's mass shooting in Roseburg, Oregon.
Volkwagen's top U.S. executive testified Thursday that emissions-cheating software in diesel cars was the work of "a couple of software engineers."
The U.S. asked NATO allies on Thursday for flexibility as the alliance reviews its plans to rapidly withdraw troops from Afghanistan.
What's behind the spate of "lone-wolf" stabbings, unrest and clashes in Israel and the West Bank have left least 10 dead in one week.