REUTERS

Washington has become increasingly concerned at North Korean missile and nuclear tests and threats to its neighbors and the U.S., the BBC wrote.

The briefing, involving 100 senators as well as Secretary of State Rex Tillerson and Defense Secretary James Mattis, is being held on Wednesday.

China, North Korea's main ally, has called for restraint from all sides.

China's call came in a phone conversation between President Xi Jinping and President Donald Trump on Sunday.

Mr. Xi urged all parties to "maintain restraint and avoid actions that would increase tensions", according to the Chinese foreign ministry.

Read alsoRussia reportedly moving military equipment toward North Korean borderFor his part, Mr. Trump said North Korea's "continued belligerence" was destabilizing the Korean peninsula.

White House officials regularly go to Congress to brief on national security matters, but it is unusual for the whole Senate to go to the White House.

Read alsoU.S. tells N. Korea: We don't want a fight, don't start one – APAlongside Mr. Tillerson and Gen Mattis will be National Intelligence Director Dan Coats and Gen Joseph Dunford, chairman of the Joint Chiefs of Staff.