WASHINGTON — The FBI has arrested 10 people for allegedly serving for years as secret agents of Russia's intelligence service, the SVR, with the goal of penetrating U.S. government policymaking circles. According to court papers unsealed Monday, the FBI intercepted a message from SVR headquarters, Moscow Center, to two of the defendants describing their main mission as "to search and develop ties in policymaking circles in US." Intercepted messages showed they were asked to learn about a broad swath of topics including nuclear weapons, U.S. arms control positions, Iran, White House rumors, CIA leadership turnover, the last presidential election, Congress and the political parties. After a secret multiyear investigation, the Justice Department announced the arrests Monday in a blockbuster spy case that could rival the capture of Soviet Col. Rudolf Abel in 1957 in New York. There was no clue in initial court papers how successful the agents had been.