Image credit: Mass Communication Specialist 3rd Class Ryan D. McLearnon/U.S. Navy

Nearly 50 miles from Iran sails the nuclear-powered USS Eisenhower - never before has the U.S. flexed so much muscle so close to the Muslim nation.

The move is a blunt warning to Iran: Don't follow through on a threat to close the Strait of Hormuz, through which one-fifth of the world's oil passes.

If Israel attacks Iran's nuclear sites, Iran has promised to fill the strait's waters with boats packed with explosives and mine the seabed.

"A $1,500 piece of explosive can take out hundreds of millions of assets in shipping and cargo," said Rear Adm. Michael Manazir, commander of Carrier Strike Group Eight.

With more jets, ships and nations - 30 - involved than in previous exercises, the U.S. has sent two aircraft carriers into the region.

Each carries more than 40 F-18 fighter jets that could reach thousands of miles into Iranian air space. In addition, each fighter jet has more firepower than the entire Iranian Air Force.

The international show of force is meant to reassure Israel and persuade Iran to not try anything - even if it is attacked.

The U.S. hopes that tensions will ease, but Israel has warned that Iran's capital, Tehran, is only six months away from a potential nuclear weapon.

"As you can see, I can do a lot of damage with the airplanes that are onboard - also the weapons that are in the strike group," Manazir said. "But also, I can be a stabilizing influence."

Even after the exercise ends, though, the troops and additional assets will remain in the region to remind Iran that the U.S. can act just a few miles from its shores.