Trump taps former acting AG Matthew Whitaker as NATO ambassador

The appointment Wednesday comes at a significant juncture for the alliance. 

Russian President Vladimir Putin on Tuesday formally lowered the threshold for the Kremlin's use of its nuclear weapons, a move that follows President Biden's decision to let Ukraine strike targets inside Russian territory with American-supplied long-range missiles.

The new doctrine allows for a potential nuclear response by Moscow even to a conventional attack on Russia by any nation that is supported by a nuclear power.

Putin first announced changes in the nuclear doctrine in September, when he chaired a meeting discussing the proposed revisions. He has previously warned the U.S. and other NATO allies that allowing Ukraine to use Western-supplied longer-range weapons to hit Russian territory would mean that Russia and NATO are at war.

Whitaker served as Acting Attorney General from November 2018 to February 2019.

That was after Attorney General Jeff Sessions resigned at Trump's request amid Special Counsel Robert Mueller's investigation into alleged Russian collusion by the Trump campaign. Whitaker was Sessions' chief of staff and was critical of the probe. 

Trump later nominated Bill Barr as the permanent replacement to head the Justice Department following Sessions' departure.

The Associated Press contributed to this report.