Expanding his attack on the administration's nuclear deal with Iran, Sen. Ted Cruz Thursday said that President Obama should end talks, demand Tehran give up its nuclear program immediately and use military force if the terrorist nation doesn't give in.

A "responsible president," the Texas Republican told a conference on Iran's grab for a nuclear weapon, "would stand up and say unequivocally, in terms that allow no confusion, 'Under no circumstances will the nation of Iran be allowed to acquire nuclear weapon capability, and they will either halt now or we will use every step necessary including direct military force to stop them.'"

But, said Cruz, mulling his own 2016 Republican presidential bid, "that leadership is desperately needed, and right now that leadership is not there."

Cruz, one of the Senate's harshest critics of the U.S. deal to trade sanctions on Iran in exchange for drawing down its nuclear weapons program, also said that the United States should arm Israel with so-called "bunker buster" bombs capable of destroying Iran's bomb plants deep below the surface of the earth.

"At a very minimum," the first-term senator said, "we should be making available bunker busters to Israel. That if Israel is going to be forced to defend itself, it should have the tools to effectively eliminate this program."

Cruz also called for swift approval of new and broader economic sanctions in Iran.

He called the deal being discussed in Geneva and pushed by Secretary of State John Kerry "a very very bad deal and an historic mistake" and a lethal threat to Israel.

Instead of "appeasement," Cruz said, "we should act against an enemy of the United States."

Critics worry that the administration's Iran deal would leave that country with the ability to use nuclear energy that could quickly be modified for bomb-making.

"The threat of a nuclear Iran is the gravest national security threat to the United States of America in the world," Cruz warned, adding that he believes the minute Iran builds a bomb, it will use it against Israel, Los Angeles or New York. "That threat, I think, is enormous."

And just as bad, he said, is the potential for Iran to share the technology with terrorist groups or Muslim foes of Israel.

R. James Woolsey, a former CIA director, said at the conference that Iran is close to making a bomb and that "it's the United States' duty to deal with this … we have very little time."

Paul Bedard, the Washington Examiner's "Washington Secrets" columnist, can be contacted at pbedard@washingtonexaminer.com.