Ronald W. Pelton. A communications specialist with the National Security Agency 1965-79. Mr. Pelton was arrested by Federal Bureau of Investigation Agents in Annapolis, Md., yesterday. At the time of this writing, he was scheduled for a hearing in a Baltimore Federal Court on charges of conspiring to pass secrets to the Soviet Union. Pelton's espionage activities may have been revealed to US authorities by Vitaly Yurchenko, the Soviet KGB agent who defected to the US and then returned to Russia. Larry Wu-Tai Chin. A Central Intelligence Agency analyst 1952-81. Mr. Chin was arrested by FBI agents last Saturday and charged for spying for the Chinese. He apparently began spying while serving as an intrepeter for interrogators of Chinese prisoners during the Korean war. At the time of his retirement, he was a midlevel employee of the Foreign Broadcast Information Service, a division of the CIA that analyzes foreign broadcasts. Jonathan J. Pollard. A civilian employee of the Naval Investigative Service, a branch of Naval Intelligence that conducts background checks of personnel and is also responsible for counterintelligence activities. Mr. Pollard and his wife Anne were arrested by the FBI last week and are charged with communicating US secrets to a foreign government, which officials have identified as Israel. Edward L. Howard. An employee of the State Department's Agency for International Development 1976-79 and an employee of the CIA 1981-83. Mr. Howard's alleged identity as a spy for the Soviet Union was apparently revealed by defected Soviet KGB agent Vitaly Yurchenko. Howard disappeared in September and is believed to have defected. Howard may have tipped the Soviets to the identity of a Soviet aeronautical engineer who had been giving the US information on Russian advanced aircraft programs. Sharon M. Scranage. A clerk for the CIA 1983-85. Ms. Scranage was convicted this fall of revealing the identities of two CIA covert agents to her Ghanaian boyfriend while she was assigned to the US Embassy in Ghana. John A. Walker Jr. Retired US Navy warrant officer who confessed to having masterminded a spy ring for the Soviets for nearly two decades. In October, Walker was sentenced to life in prison. Michael Walker. A US Navy seaman who confessed that while he was stationed aboard the aircraft carrier USS Nimitz, he provided classified material to his father's spy operation. In October, he was sentenced to 25 years in prison. Arthur J. Walker. A retired US Navy lieutenant commander who was convicted for his participation in his younger brother's spy ring. This month Walker was given a life sentence for his espionage activities. Jerry Whitworth. A retired US Navy chief petty officer. Mr. Whitworth, a specialist in naval communications and cryptology, is the alleged fourth member of the Walker spy ring and is scheduled to go on trial in January. Richard M. Miller. A 20-year veteran of the FBI who worked as a specialist in counterintelligence. Mr. Miller's trial for allegedly passing secrets to Soviet agents was declared a mistrial earlier this month. Samuel L. Morrison. A civilian intelligence analyst for the US Naval Intelligence Command. Morrison was convicted in October for giving US intelligence satellite photographs to a military publication in Britain.