Army Secretary Mark Esper may have been an unexpected choice for defense secretary, but his nomination on Friday is not surprising given his behind-the-scenes ties to the White House.

Esper knows Secretary of State Michael Pompeo well — the two were both Class of 1986 graduates of the U.S. Military Academy, known as West Point. Pompeo has gotten at least two other West Point colleagues into the administration — Ulrich Brechbuhl and Brian Bulatao at the State Department.

Esper has also known National Security Adviser John Bolton for years. Esper served as deputy assistant secretary of defense for negotiations policy in the George W. Bush administration when Bolton served as under secretary of state for arms control and international security.

Esper also has a strong backer in Army Chief of Staff Gen. Mark Milley, who is slated to become the next chairman of the Joint Chiefs of Staff and the president’s top military adviser.

There are also others in the White House orbit who have ties to the Army. David Urban, a high-powered Washington, D.C. lobbyist who is also a Class of 1986 graduate of West Point, ran Pennsylvania for Trump in the 2016 campaign.

The Army’s ties to the White House were apparent at a December 2018 party at the St. Regis Hotel in Washington, DC, where top Trump advisers, administration officials, members of Congress, and a small number of media including Breitbart News, were present.

Esper and Milley were in attendance, as were Army Under Secretary Ryan McCarthy and former Army secretary nominee and Florida Panthers owner Vincent Viola, another West Point graduate. At one point during the evening, Pompeo, Milley, Esper, Urban, Viola, McCarthy, and several other Army veterans posed for a group photo.

With Milley, Esper, and Pompeo serving on the president’s national security team, the Army is poised to have a team similar to that of the Marines when former Defense Secretary and retired Gen. Jim Mattis, Chairman of the Joint Chiefs of Staff Gen. Joseph Dunford, and Retired Gen. John Kelly served together.

Some experts say it is merely coincidence. But others say the groundwork was strategically laid.

According to a U.S. official, Mattis had wanted as the next chairman of the Joint Chiefs of Staff Air Force Gen. David Goldfein, whom Mattis had gotten to know when he was the commander of Central Command and Goldfein was commander of Air Forces Central Command.

But a coalition of Army veterans — including Sen. Tom Cotton (R-AR), Vice President Mike Pence’s National Security Adviser Retired Lt. Gen. Keith Kellogg, Pompeo, Esper, and Urban — all lobbied for Milley to get the position, according to the official.

However, since the beginning of Trump’s tenure, Milley himself has also not shied away from forging a relationship with the president. Milley notably sat next between the president and Pence during Trump’s inauguration ceremony and has a wall of photos with himself and the president at his residence, Quarters One at Fort Myers-Henderson Hall.

The close relationship between Milley and the Trumps could also be seen at the most recent Army Ten Miler, when Ivanka Trump and Jared Kushner ran in the annual event. Before the race, Milley, his wife Hollyanne, and Esper, took photos with Trump and Kushner, who donned Army hats.

So far, Esper’s nomination appears headed for success, with key voices of support rolling in, including from fellow Army veterans

Senate Armed Services Committee Chairman Jim Inhofe (R-OK), an Army veteran, praised Trump’s nomination of Esper for defense secretary.

“President Trump has made a good decision in having Secretary Esper serve as Acting Secretary of Defense. Secretary Esper has a long history of dedicated service to this nation, and he has shown excellent judgment in his current position, which I expect will continue as he assumes the role of Acting Secretary of Defense,” he said in a statement.

Sen. Joni Ernst (R-IA), a retired Army National Guard colonel and chairman of the Senate Armed Services Subcommittee on Emerging Threats and Capabilities, praised Esper.

“It’s critically important that we have a Senate confirmed secretary of defense, especially given the growing tensions with Iran. I’ve worked closely with Mark Esper in his role as Secretary of the Army and believe he has demonstrated strong leadership,” she said in a statement.

Esper is also attracting bipartisan support. House Armed Services Committee Chairman Adam Smith (D-WA) also said he was “encouraged” that Esper has a “track record of public service both as a soldier and in government.”

“If confirmed, I am confident that Secretary Esper is capable of executing the national defense strategy in a way that is insulated from outside influence and political considerations,” he said. “I have known Esper for years, both as a staff member on the Hill and in private industry, and believe the Department would benefit from his leadership. I look forward to our continued work together.”

Esper began his career as an infantry officer in the 101st Airborne Division after graduating from West Point in 1986. He served in the first Gulf War. He later transitioned to the National Guard and retired after 21 years. He worked on Capitol Hill for Sens. Chuck Hagel (R-NE), Fred Thompson (R-TN), and Majority Leader Bill Frist (R-TN).

He also served on the Senate Foreign Relations and House Armed Services Committees, and as a deputy assistant secretary of defense under the second Bush administration. In the private sector, he served as executive vice president at the U.S. Chamber of Commerce, on Thompson’s presidential campaign in 2008, as executive vice president of the Aerospace Industries Association of America.

He also served as chief of staff at the Heritage Foundation, a conservative think tank. Before becoming Army secretary, he served as a vice president for government relations at the Raytheon Company.

He is a graduate of West Point, Harvard University John F. Kennedy School of Government, and George Washington University.

Esper took over for former acting Defense Secretary Patrick Shanahan Sunday at midnight.

This piece has been updated.