My fellow Americans: When I first swore the oath of office as your president almost six years ago, I committed to "preserve, protect and defend the Constitution of the United States." This duty compels me to address a growing threat to our nation, and to explain to you why and how we must do so.

President Bush leaves the White House, Monday, Nov. 27, 2006, to attend a NATO summit Tuesday and Wednesday in Latvia.
Photo: AP , AP

Twenty-seven years ago, a revolutionary regime came to power in Iran. The new regime promised to free the people, end corruption, and advance religion.

Not all revolutions, as we learned from the bitter experience of the last century, deliver what they promise.

In November 1979, within weeks of taking power the US embassy in Teheran was raided and our diplomats were taken hostage. The new government, while disassociating themselves from the "students" who attacked sovereign US territory, did nothing to free our diplomats, who remained hostage for 444 days. This assault established, from the beginning, the regime's disdain for the fundamental premises of our nation state system.

Soon after, the Iranian regime ordered the capture of more American diplomats in Beirut, and arranged for suicide bombings against American peacekeeping forces in Lebanon, killing 300 Americans, including 241 Marines.

We must admit that, as a nation, we did not respond adequately to these unprovoked assaults. Iran drew the conclusion that it could take the next step and, in 1987, attempted to block the flow of oil through the Persian Gulf by firing on Kuwaiti tankers. Only after the United States took Kuwaiti tankers under our own flag, dispatched a naval task force, sank half the Iranian navy, and dismantled Iranian offshore oil facilities did the Iranian regime halt its offensive.

Even this decisive action only temporarily dissuaded the regime from pursuing its ambitions, which were not only regional, but global. In 1989, the collapse of the Berlin Wall led Ayatollah Khomeini to write to taunt Soviet leader Mikhail Gorbachev, "I openly announce that the Islamic Republic of Iran, as the greatest and most powerful base of the Islamic world, can easily help fill up the ideological vacuum of your system."

By 1990, the regime worked actively to create an "arc of crisis" from India to North Africa. It established or strengthened branches of Hizbullah in 17 countries and backed older radical Islamist groups in Central Asia, Afghanistan, and the Arabian Peninsula.

Year after year, Iran topped the State Department's roll of infamy: states that sponsor terrorism.
On July 12, Hizbullah crossed the Lebanese border and kidnapped two and killed eight Israeli soldiers. Iran hoped that Hizbullah's aggression would intimidate the G-8 nations into abandoning efforts in the UN Security Council to halt Iran's rush to obtain nuclear weapons. It did not, nor did the thousands of Iranian and Syrian missiles pointed at Israel's cities deter her from responding.

Iran is actively supporting terrorist militias that are attacking Israel and attempting to make Iraq, Lebanon and Afghanistan ungovernable. The regime's purpose is clear: to intimidate free nations into standing by as it develops nuclear weapons - after which it will further escalate its campaign of terror with impunity. As Iranian President Mahmoud Ahmadinejad explained on September 28, Iran "has the capacity to quickly become an invincible global power. This will happen as soon as it achieves advanced technologies."

Of late, former American officials for whom I have great respect, and my good friend and ally Tony Blair have both suggested that the only solution to the situations in Iran, Iraq, Lebanon, and Israel is a regional one. I entirely agree. It is impossible to put out a fire in one place and expect that fire not to appear in another, especially when the nation that is the main source of the fire has not been addressed.

It is clear, however, that simply appealing to nations such as Iran and Syria to stop setting these fires will be ineffective, and could even encourage these nations to commit further aggression. Similarly, the notion that the century-old Arab-Israeli conflict must be solved as a means to address the Iranian threat is backward: so long as Iran uses its proxies to set fires in Lebanon and Gaza, all attempts to strengthen moderate forces will falter.

IN 1936, a single French division could have stopped Adolf Hitler's occupation of the Rhineland. In 1938, France, Britain and the Czech army could have defeated Hitler, rather than handing Czechoslovakia over to the Nazi regime. Prudent action could have prevented World War II, saving 60 million lives, including the six million Jews murdered in the Holocaust.

We stand at a similar juncture in history. A radical Islamist Iran is potentially even more dangerous than Nazi Germany was for three reasons: it could succeed in obtaining nuclear weapons; it operates through terrorist proxies, not just its own army; and it aspires to lead not just one state, but to mobilize the entire Islamic world.

I turn to our friends in Europe: UN Security Council Resolutions 1373 and 1540 already call on all member states to block funds and services that could contribute to terrorism or the development of weapons of mass destruction. Let us together, now, impose stiff sanctions on Iran. The faster and more seriously we take non-military action, the greater the hope of averting the need for military action in the future.

My fellow Americans, the incineration of 3,000 of our citizens five years ago demonstrates that our enemy's imagination knows no moral limits. What began with the occupation of an embassy has escalated into threats to wipe a state, Israel, off the map, and threatens to place our entire nation under a nuclear shadow.

In 1938, after the Munich agreement, Winston Churchill told the House of Commons: "Britain and France had to choose between war and dishonor. They chose dishonor. They will have war."

We do not yet have to choose war. It is precisely to prevent war that must act together and immediately, or stand by as our options dwindle along with our freedom and security.