NEW YORK (AP) – The Central Intelligence Agency can force Valerie Plame Wilson, whose CIA career became national news after her once-clandestine position was leaked to the media, to remain silent about the exact lenghth of her tenure with the agency, a federal judge has ruled.

Although the years of her CIA employment have appeared in the Congressional Record and elsewhere, U.S. District Judge Barbara S. Jones said in ruling for the CIA that there were benefits to the agency and the country in keeping some things classified – even after they are seemingly public.

Wilson and her publisher, Simon & Schuster, brought the lawsuit earlier this year, saying they had a First Amendment right to publish her dates of employment with the CIA in her upcoming memoir.

But the judge said their arguments placed “far too much emphasis on public perception, and ignores the compelling considerations of the CIA’s commitment to secrecy and matters of foreign relations.”

Simon & Schuster, in a statement, said it was considering its legal options and still planned to publish Wilson’s “Fair Game.”

“We are disappointed in the court’s ruline, which we believe runs counter to the First Amendment, sets a dangerous precedent and creates an unreasonable standard by which the government can disappear public information and rewrite history,” the company said.

Wilson’s identity was revealed in a syndicated newspaper column in 2003, shortly after her husband, a former ambassador, began criticizing the administration’s march to war in Iraq.

According to published reports, including in the Congressional Record, the former CIA operative worked at the CIA from 1985 to 2006. The government has publically acknowledged that she worked for the CIA from 2002 to January 2006.

“Information concerning Wilson’s pre-2002 employment for the CIA (if any) is properly classified, has never been declassified, and was not otherwise officially acknowledged by the CIA,” Jones said.

Jones said the CIA had convinced her in statements by its deputy director, Stephen Kappes, that national security could be harmed if the agency acknowledged whether the information at issue in the case was true.

The judge, in a decision dated Wednesday and entered into the public record Friday, wrote that the government cannot be forced to divulge information that has never been officially released from classified status.

“Sound policy compels this distinction,” she wrote. “When a disclosure is unofficial, the world at large is left to surmise whether the information is accurate. Leaving the public to guess carries some degree of protection to confidentiality.”

Jones said the CIA “confirms its commitment to secrecy when it does not officially disclose or acknowledge public information.” That commitment, she ruled, “serves not only to protect former and existing intelligence sources and methods, but also serves to maintain the confidence of would-be recruits and co-operators.”

In the world of international diplomacy, she added, official confirmation of public information can have a negative effect on U.S. relations with foreign countries.

Messages left with lawyers for Wilson and Simon & Schuster were not immediately returned. Yusill Scribner, a spokeswoman for government lawyers, said they would have no comment.