U.S. intelligence chief says Islamic militants will continue plotting against U.S. interests overseas and homegrown attacks will pose the most significant threat to Americans at home.

Director of National Intelligence James Clapper is delivering the annual assessment by intelligence agencies of the top dangers facing the country.

In an opening statement Tuesday to the Senate Armed Services Committee, Clapper says that the perceived success of attacks by homegrown violent extremists in Europe and North America — such as those in Chattanooga, Tennessee, and San Bernardino, California — might motivate others to replicate the attacks. That would diminish the U.S. ability to detect terrorist operational planning and readiness, he said.

Clapper also said Iran remains the top state sponsor of terrorism and al-Qaida-linked groups remain resilient. He said the U.S. will continue to see cyber threats from China, Russia and North Korea.