Like characters in Mad magazine's cartoon strip "Spy vs. Spy," Henry Kissinger and reporter Seymour Hersh are following each other's tracks around Washington.

Hersh, working on a book that will be critical of Kissinger's reign as secretary of state and national security adviser, is using the Freedom of Information Act to obtain documents related to Kissinger's government performance. And Kissinger -- who has fought in court efforts by researchers using the Freedom of Information Act to glimpse his government files -- is himself using the law to learn what documents Hersh is receiving.

Shortly after Christmas, attorney Bruce Chadwick of Arnold & Porter wrote the General Services Administration on behalf of Kissinger. His query: a copy of all requests for documents and copies of actual documents released to Hersh and British journalist William Shawcross. (Published last year, Shawcross' book, Sideshow, attacked Kissinger's involvement in the devastation of Cambodia in the 1970s.)

Apparently, the GSA didn't jump fast enough for Kissinger's lawyer. Less than a month later Chadwick telephoned and wrote the GSA asking its director of information to expedite Kissinger's request for information.

Chadwick refused to comment on why his famous client was so interested in Hersh's inquiries, but the former New York Times reporter -- who received a $200,000 advance for his book from Random House -- is mildly amused by the affair.

"If I were Henry Kissinger," says Hersh, "I'd be worried sick."