PENTAGON (VOA) - At a news conference, Admiral Mike Mullen refused to reveal any substance from his recent meetings in Israel, which came shortly after Israeli forces had conducted an extensive exercise that many interpreted as preparation for an air strike on Iran's nuclear facilities. But Admiral Mullen warned that any "destabilizing acts" could have unpredictable consequences, and it would be difficult for the United States to respond.

"Opening up a third front right now would be extremely stressful on us," said Admiral Mullen. "That doesn't mean we don't have capacity or reserve. But that would really be very challenging and also the consequences of that, sometimes, are very difficult to predict."

The admiral says that is why he prefers the current U.S. and international policy of trying to convince Iranian leaders to abandon their nuclear weapons program through a package of incentives and punishments.

Admiral Mullen, who is Chairman of the Joint Chiefs of Staff, spoke just a few days after news organizations quoted an unnamed senior defense official as saying there is increased likelihood of an Israeli attack on Iran before the end of the year. The official was quoted as saying Israel believes if it waits any longer, Iran will have a nuclear weapon or a sophisticated air defense system, or both. Admiral Mullen says Israel has predicted faster Iranian progress than American analysts have.

Admiral Mullen was asked whether there is "a high stakes bluffing game" going on.

"It is high stakes, it's no question, in this part of the world," he said. "And I guess I'd just leave it at that."

Admiral Mullen also endorsed comments earlier Wednesday by the U.S. Naval commander in the Middle East. Admiral Kevin Cosgriff said the United States will not allow Iran to close the Straits of Hormuz, at the entrance to the Persian Gulf, as Iran has threatened to do if it is attacked. Admiral Mullen said Iran has the ability to create a "hazard" in the Straits, but not to sustain it against U.S. forces.