U.S. intelligence officials assess that Russia and China are working more closely together on military issues, including a potential invasion of Taiwan, prompting new planning across the government to counter a potential scenario in which the countries fight in coordination.

"We see China and Russia, for the first time, exercising together in relation to Taiwan and recognizing that this is a place where China definitely wants Russia to be working with them, and we see no reason why they wouldn’t,” Director of National Intelligence Avril Haines said Thursday in testimony to Congress.

Republican Sen. Mike Rounds of South Dakota asked Haines about such a potential scenario during a hearing of the Senate Armed Services Committee. He also asked the head of the Defense Intelligence Agency about the Pentagon’s planning for such a possibility.

The Defense Department has "become even more concerned about our joint force requirements in an environment where” Russia and China "would certainly be cooperative, and we need to take that into account,” Lt. Gen. Jeffrey Kruse responded.

Rounds said that the "the bottom line is that, basically, if we were to have a conflict with one, chances are that we would have a second front,” affecting planning, equipment and manpower needs.

"Certainly it’s a possibility,” Haines said. "The question of just how likely it is, I think differs depending on the scenario.”

Haines added that intelligence assessments indicate there is "increasing cooperation in the ‘no-limits’ partnership” between Russia and China "across really every sector of society: political, economic, military, technological and so on.”