Move harkens back to 1981 exchange of cash for Americans held at Tehran embassy; simmering tensions between nations ratchet up consequences should contacts fail

Tehran objects to takeover of Suez Rajan as 'completely unproductive' as countries try to work toward exchange of American prisoners for release of frozen Iranian assets

As Washington and Tehran near potential prisoner exchange deal, tensions remain high around Strait of Hormuz, with increased seizures by Iran and boosted US naval presence

Move could deter Iran or escalate tensions further and would represent extraordinary commitment in Mideast by US forces, as Pentagon tries to focus on Russia and China

Officials say no final decision made, deployments would be made at request of ships involved; drastic move not even taken during 'Tanker War' in 1980s

Washington has sent ships, planes and marines to boost security around Strait of Hormuz, where Tehran has resumed harassing and seizing ships trying to pass through vital waterway

Defense chief okays deployment of amphibious readiness group and some 2,500 Marines after Iranian attempts to seize tankers, joining destroyer and fighters recently sent to region

Iran tried to seize two oil tankers near the Strait of Hormuz last week, opening fire on one of them

Attack is the latest in a string of attempts by the Islamic Republic to seize commercial vessels passing through the strategic Strait of Hormuz

Comments by Tehran's army chief come days after US, French and UK naval commanders transit through Strait of Hormuz aboard American warship in rare show of force