MOSCOW — A new law expanding Russia's definition of treason took effect Wednesday — and critics say it's so vague that the government can now brand anyone who dissents as a traitor.

Under the new law, anyone possessing information deemed secret — whether a politician, a journalist, an environmentalist or a union leader — could potentially be jailed for up to 20 years for espionage.

Human rights advocates say the law is part of a widening crackdown on the opposition after President Vladimir Putin began his third presidential term in May.