The major step is the culmination of several festering stand-offs between the International Atomic Energy Agency and Iran.

Iran has warned it will ramp up its nuclear activities after the United Nations nuclear watchdog’s 35-member board of governors adopted a resolution Thursday declaring it in breach of its non-proliferation obligations.

Iran says it has built and will activate a third nuclear enrichment facility, ratcheting up tensions with the U.N. immediately after its atomic watchdog censured Iran for failing to comply with obligations meant to prevent it from developing a nuclear weapon.