Lt. Col. Ralph Peters (Ret.) said President Donald Trump made a "great" choice by picking Lt. Gen. H.R. McMaster, but warned that Washington, D.C., is a "different battlefield."

Peters said in war, you know who your enemies are, but in Washington "you can't trust anybody."

"A new guy is walking barefoot through a snakepit. I think the greatest risk for him personally is that lack of Washington experience. I'm hoping he can surmount it," said Peters.

He also warned against the United States developing a "target lock" on the Middle East when it comes to foreign policy decisions, pointing out that most of McMaster's military experience is in the Middle East.

Peters said experts are also needed on NATO, China, Latin America and other areas so that "even graver dangers" are not ignored.

He said McMaster will need people like Republican Senators John McCain, Lindsey Graham and Tom Cotton to "help him learn the ropes of negotiating outside the White House."

"Inside the White House, [McMaster] has such forceful, strong character and sense of integrity, he'll be able to stand up to anybody. He won't just go along," said Peters.

McMaster replaces Gen. Michael Flynn [Ret.], who resigned last week amid a controversy over his contact with Russian officials.

McMaster, 54, is a three-star general who served in the Persian Gulf as a well as the War on Terror, and is the recipient of more than a dozen military service awards.

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