House Intelligence Committee Chair Mike Turner has made intelligence around a “serious national security threat” available to all members of Congress to review. Two sources familiar with the matter and a US official tell CNN the threat is related to Russia.

Multiple sources familiar with the intelligence characterized the intelligence as “very sensitive.”

Earlier Wednesday, Turner sent his Congressional colleagues a letter saying the urgent matter is “with regard to a destabilizing foreign military capability.”

One of the sources who has seen the intelligence confirmed that “it is, in fact, a highly concerning and destabilizing” Russian capability “that we were recently made aware of.”

Turner said in the dear colleagues letter that the House Intelligence Committee voted on February 13 to make certain information available for lawmakers to review and says members have time to view this between Wednesday and Friday.

Turner is also calling on President Joe Biden to declassify “all information relating to this threat.”

National Security Adviser Jake Sullivan said he had personally reached out to set a meeting with top lawmakers on national security committees before Turner warned publicly of what he termed the “serious national security threat.”

“I reached out earlier this week to the Gang of Eight to offer myself for up for a personal briefing to the Gang of Eight and, in fact, we scheduled a briefing for the for House members of the Gang of Eight tomorrow,” Sullivan said from the White House. “That’s been on the books. So I am a bit surprised that Congressman Turner came out publicly today in advance of a meeting on the books for me to go sit with him alongside our intelligence and defense professionals tomorrow.”

Sullivan said he remained focused on sitting down with Turner on Thursday for the meeting.

He declined to elaborate on the nature of the threat.

“I’m not in a position to say anything further from this podium at this time,” he said.

He emphasized the Biden administration has “gone further and in more creative, more strategic ways, dealt with the declassification of intelligence in the national interest of the United States than any administration in history.”

“So you definitely are not going to find an unwillingness to do that when it’s in our national security interest to do so,” he said