Secretary of State Hillary Clinton got one thing right last week - she described WikiLeaks' disclosure of hundreds of thousands of classified documents as "an attack." Indeed, it was the third such attack in five months that WikiLeaks has launched against the United States and its international partners. WikiLeaks itself has described its struggle in military terms. Founder Julian Assange recently posted a Tweet from one of his supporters declaring: "The first serious infowar is now engaged. The field of battle is WikiLeaks. You are the troops."

Like the war on terror, we have been attacked in this new cyber war in ways we did not anticipate. Over the past decade, the U.S. government has spent billions to stop foreign adversaries from remotely penetrating our computer networks for sabotage. Instead of trying to break through these defenses, Assange pioneered a new form of cyber sabotage. He found someone who allegedly penetrated our classified systems from within, downloaded America's secrets onto a Lady Gaga CDand gave them to Assange, who then disseminated this stolen information across the world.

Assange has made clear he intends to continue posting stolen classified information and has effectively dared the United States and the world to try and stop him. He recently announced through his lawyer that if he is arrested, he will unleash a "thermonuclear device" of completely unexpurgated government files. Think about that: Assange has threatened America with the cyber equivalent of thermonuclear war.

If WikiLeaks is treating this as a war in cyberspace, America should do the same. The first step is to rally a coalition of the willing to defeat WikiLeaks by shutting down its servers and cutting off its finances. WikiLeaks' most recent disclosures - which exposed not only America's secrets but also those of other nations - seem to have awakened others to the threat the group poses.

In recent days, WikiLeaks has had trouble staying online - in part because governments have been pressuring companies to stop hosting WikiLeaks. In the United States, Amazon.com kicked WikiLeaks off of its servers after an aide to Joe Lieberman, chairman of the Senate Homeland Security and Governmental Affairs Committee, complained. Another U.S. provider, EveryDNS.net, kicked WikiLeaks off as well, and PayPal.com cut off the account WikiLeaks had been using to collect donations.

In France, Industry Minister Eric Besson said the government would force a French company, OVH SAS, to stop hosting WikiLeaks, declaring, "France cannot host Internet sites that violate the secrets of diplomatic relations and endanger people protected by diplomatic secrecy." Other countries should be encouraged to follow suit.

As WikiLeaks is driven from the cyber territory of responsible countries, it will seek refuge elsewhere on the Internet, setting up operations in nations where it believes it will receive protection. Governments that provide WikiLeaks with virtual safe havens should be told in no uncertain terms: "You are either with us, or you are with WikiLeaks." If they refuse to shut WikiLeaks down on their territory, action should be taken to drive WikiLeaks from those safe havens.

Last week, a Pentagon spokesman confirmed that the United States does in fact have the offensive capabilities in cyberspace to take down WikiLeaks, but that the Obama administration chose not to use them. This failure to act prompted a patriotic hacker who goes by the name th3j35t3r (the Jester) to attack WikiLeaks himself, repeatedly taking down its Web site.

If "one guy with a laptop" can shut down WikiLeaks even temporarily, imagine what the 1,100 cyber-warriors at U.S. Cyber Command could do. While the United States sits on the sidelines, the New York Times reported Saturday that WikiLeaks had come under assault "from armies of zombie computers in Europe, Russia and Asia." This flood of attacks creates the perfect cover for the United States to deliver the coup de grace to WikiLeaks secretly, with no fingerprints, if it chose to do so.

Some say attacking WikiLeaks would be fruitless. Really? In the past year, the Iranian nuclear system has been crippled by a computer worm called "Stuxnet," which has attacked Iran's industrial systems and the personal computers of Iranian nuclear scientists. To this day, no one has traced the origin of the worm. Imagine the impact on WikiLeaks's ability to distribute additional classified information if its systems were suddenly and mysteriously infected by a worm that would fry the computer of anyone who downloaded the documents. WikiLeaks would probably have very few future visitors to its Web site.

WikiLeaks represents a new and unprecedented cyber threat that cannot be ignored or wished away. Just as terrorism allows small groups of individuals to wreak destruction on a scale that was once the province of nation-states, information technology allows small actors such as Julian Assange to wreak previously unimagined destruction on U.S. national security through cyberspace. This is a threat that requires aU.S. response. Hillary Clinton is right - WikiLeaks has attacked America. The only question is: Will America return fire?

Marc A. Thiessen, a visiting fellow with the American Enterprise Institute, is the author of the book "Courting Disaster." He writes a weekly column for The Post.