China’s Foreign Ministry denounced the criminal case as “pure fabrication,” but it has neither confirmed nor denied that Mr. Xu was an intelligence officer. China’s relatively muted reaction could be an effort to minimize attention on an embarrassing intelligence failure and leave room for quiet negotiations for an exchange.
Mr. Xu’s was the most high profile of several recent cases, including two others that had links to the Ministry of State Security’s branch in Jiangsu Province, which extends north from Shanghai.
In September, the Justice Department announced the arrest of Ji Chaoqun, a 27-year-old graduate student who had joined the Army Reserves under a special waiver for foreigners.
The F.B.I. affidavit in the case said that Mr. Ji’s handler — presumably Mr. Xu — had been arrested, allowing the bureau to send an undercover officer to meet the student in April. Mr.