Article Photos: Tensions high, U.S. warns Iran not to block shipping 4/5

FILE - In this Jan. 12, 2012 file photo, Joint Chiefs Chairman Gen. Martin Dempsey speaks at Duke University in Durham, N.C. Tensions flaring, the Obama administration warns Iran through public and private channels against any action that threatens the flow of oil from the Persian Gulf. Some experts fear the risk of open conflict with Tehran appears higher than at any point since President Barack Obama took office, perhaps from U.S. moves to enforce open shipping through the Strait of Hormuz or even a military strike from Israel.  (AP Photo/Jim R. Bounds, File) ORG XMIT: WX105