In potentially the most significant attack on WikiLeaks to date, PayPal on Friday froze the account of the German foundation accepting donations for the secret spilling website, claiming that WikiLeaks was in violation of PayPal's terms of service.

"PayPal has permanently restricted the account used by WikiLeaks due to a violation of the PayPal Acceptable Use Policy, which states that our payment service cannot be used for any activities that encourage, promote, facilitate or instruct others to engage in illegal activity," reads a statement on PayPal's website. "We’ve notified the account holder of this action."

Most of the over $1 million in contributions WikiLeaks has drawn in the last year have come through its PayPal account, which belongs to the Wau Holland Foundation, a German non-profit group that manages the bulk of WikiLeaks' money.

Attempting to donate to Wau Holland though PayPal on Friday night produced the message "This recipient is currently unable to receive money."

PayPal's move comes amid mounting U.S. pressure against WikiLeaks over its cache of over 250,000 State Department diplomatic cables. Struggling with denial-of-service attacks on its servers earlier this week, WikiLeaks moved to Amazon’s EC2 cloud-based data-storage service, only to be summarily booted off on Wednesday. Then on Thursday its domain-name service provider, EveryDNS, stopped resolving WikiLeaks.org, after the DNS provider was battered by the DoS attacks.

There was an element of theater to WikiLeaks' supposed struggles against electronic censorship this week. WikiLeaks kept its domain hosting at EveryDNS even after the company gave WikiLeaks notice that it was pulling the plug. And though WikiLeaks has no shortage of hosting options outside of U.S. influence, founder Julian Assange selected Amazon instead, in what he described Friday as a test of the company's commitment to free speech.

The attack on WikiLeaks' money flow, in contrast, is the real deal, and has the potential to genuinely impact the organization.

PayPal's public statement doesn't detail the "illegal activity" WikiLeaks promotes, but presumably it's the leaking of classified information. Sometimes such leaks are indeed illegal. And sometimes classified leaks – legal or not – reveal warrantless wiretapping of Americans, secret CIA prison networks,and massive government waste hidden in black budgets. The reasoning PayPal offers for its newfound intolerance for WikiLeaks would seem to apply equally well to the New York Times and the Washington Post.