Deploying troops to the southern border was seen by President Trump’s detractors as a political move ahead of the 2018 midterm elections, and to his supporters as necessary for security. It was all in anticipation of a wave of migrants coming from Central America in hopes of claiming political asylum in the U.S.

Now, in internal documents obtained by Fox News and first reported by the Los Angeles Times, Marine Corps Commandant Robert Neller, a four-star general, is warning Defense Department officials that there's a cost to the massive response at the border. He called it an “unacceptable risk,” one that's “negatively impacting Marine Corps readiness.”

Sounding dire, Neller said the Marine Corps “faces fiscal challenges without precedent” for the coming fiscal year.

The memos are dated March 18 and Feb. 19, and meticulously detail the ramifications of canceling or limiting planned military exercises with allies like Indonesia, Scotland and South Korea while shifting funds to the border. That money's paying for a stepped-up military presence near ports of entry, meant to assist on-the-ground Customs and Border Enforcement officials.

Neller called the reduction and cancellation of these events “not desired nor an easy decision,” according to the memos.

The subject line of the earlier memo read: “USMC Fiscal Year 19 (FY-19) Rapidly Accelerating Risks," and was addressed to Secretary of the Navy Richard Spencer and Acting Secretary of Defense Patrick Shanahan.

In pointing out the costs and perceived perils, Neller also addressed how base damage from Hurricanes Florence and Michael has reduced the branch’s readiness.

It's expected to cost $3.5 billion to repair Camp Lejeune in North Carolina, the largest Marine Corps base on the east coast, due to the damage from Florence in September 2018.

HUNDREDS OF ILLEGAL IMMIGRANTS RELEASED INTO U.S. AMID OVERCROWDING AT DETENTION FACILITIES

Neller wrote of being frustrated at not being able to transfer money because of the planned “reprogramming” under the border emergency, stating that the Marines are short $1.3 billion for recovery operations this year (with another hurricane season looming).

“The hurricane season is only three months away,” Neller wrote, “and we have Marines, sailors and civilians working in compromised structures.”

“The Department of Defense submitted a $600 million reprogramming request to Congress on March 6th to address urgent hurricane damage repair funding shortfalls. This reprogramming request includes $400 million to repair USMC facilities. Senior DoD leaders continue daily touchpoints with the defense committees on this request, which remains in congressional action,” the Pentagon told Fox News on Thursday night.

“In addition, the FY2020 budget request fully supports all necessary hurricane damage repair incurred during the 2018 hurricane season. Furthermore, the Department is in ongoing conversations with key members of Congress about a supplemental appropriation for hurricane damage repair. With the support of and rapid action of Congress, we anticipate the Marine Corps will maintain its current high level of combat readiness.”

Trump deployed some 6,000 troops to the southern border and extended their stay through September of this year. Seen mostly as filling an assist-and-advise role for training purposes, no member of the military is legally allowed to detain individuals coming over the border.

500 Marines are deployed to the southern border, according to a Marine Corps spokesman.

In Trump’s outlined budget proposal for defense spending, announced just last week, he asked Congress to appropriate $718 billion for the Pentagon in 2020, a figure that is likely to be debated in the weeks ahead.

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Other DoD officials have testified that there is no threat at the southern border. Just last month, Gen. Terrence J. O’Shaughnessy, who leads U.S. Northern Command, told the Senate Armed Services Committee, “It is not a military threat.”

He quickly added that that doesn’t mean the military shouldn’t be involved in some way, but he didn't specify to what extent.