Just four days after U.S.-led global powers and Iran completed their nuclear deal, Ayatollah Ali Khamenei, Iran's supreme leader, reaffirmed the "Death to America" mantra that has pervaded his regime since its establishment in 1979, stating, "The entire country is under the umbrella of this great movement." Iran has killed hundreds of Americans in the Middle East, both directly and through its terrorist proxies. It has threatened U.S. regional interests by funding anti-Israeli terrorists, propping up Syria's terror-backing Bashar al-Assad and de-stabilizing U.S.-backed governments.

Moving forward, this deal will enable Tehran to threaten U.S. security more directly in at least two ways: First, Iran could deploy a nuclear warhead on one of its ballistic missiles and fire it at the United States. Iran is building increasingly sophisticated ballistic missiles, with its Shahab-3 able to reach Israel, and the Sejjil that it's developing capable of reaching Italy and Poland.

Tehran also announced plans to build missile silos in what experts consider a precursor to deploying longer range missiles.

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Second, Iran could detonate a nuclear device over the United States in an electromagnetic pulse attack that destroys our electric grid, putting the nation in the dark for months and eventually leaving 90 percent of Americans dead from disease or starvation.

Iran has tested how to conduct an EMP attack, such as by attaching a nuclear weapon to an orbiting satellite or launching a nuclear-armed missile into the atmosphere from a ship.

Iranian military leaders have endorsed an EMP attack against America, according to secret Iranian military documents that Pentagon officials have translated, and the Pentagon's North American Aerospace Defense Command is moving back into Cheyenne Mountain in Colorado because it can resist an EMP attack.

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That Iran can develop nuclear weapons under the deal, making these two scenarios plausible, is clear; the only question is when.

For starters, the deal is time-limited and, as restrictions end in 10-15 years, Iran can pursue two paths to a bomb - enriching uranium to weapons-grade levels or building plutonium-producing reactors, or both.

But Tehran need not wait that long because international inspectors will be hard-pressed to confirm that Iran is abiding by the deal's restrictions on how much uranium it's enriching, how many centrifuges it's operating, and what it may be doing at secret sites that the world has not yet discovered.

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That's because rather than "anywhere, anytime" inspections, Iran will have 24 days to comply with requests from the International Atomic Energy Agency to visit a suspected undeclared site, during which Iran can move, hide, or destroy evidence of its nuclear progress.

If Iran refuses to allow a site visit after 24 days, global leaders likely would begin further negotiations with Iran that would give the latter weeks more to clean up a site.

Nor, under this deal, must Tehran reveal the military-related dimensions of its nuclear work to date, leaving the world dangerously ignorant of how close it already is to developing and deploying a nuclear weapon and also leaving inspectors without a baseline against which to judge Iranian compliance in the future.

Moreover, the $100 billion to $150 billion in sanctions relief will give Iran a huge windfall to develop a more robust infrastructure for nuclear weapons production - either quickly by evading the weak inspections regime or more patiently by waiting about a decade until the world frees Iran of all restrictions.

Those who, in light of this deal and Iran's missile and EMP work, nevertheless dismiss the "Death to America" threats from Iran as just political rhetoric might heed the words of former Israeli Foreign Minister Abba Eban: "It is our experience that political leaders do not always mean the opposite of what they say."

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Lawrence J. Haas, a former communications director for Vice President Al Gore, is a senior fellow at the American Foreign Policy Council.