Gov. Bob McDonnell has raised concerns over automatic budget cuts in a letter to President Barack Obama, asking the president to “take direct, immediate steps” to avoid the “devastating” impacts on national security and the lives of “a great number” of Virginians and Americans.

Referred to as sequestration, and resulting from a breakdown in 2011 negotiations by the Congressional Super Committee charged with cutting spending to avoid default on the national debt, the across-the-board cuts will carve $500 billion from defense budgets for 2012-2021, on top of the $487 billion already agreed to.

“In Virginia alone, 125,000 men and women in uniform, as well as 830,000 veterans who have served our nation, rely on you as Commander-in-Chief to avert sequestration,” McDonnell wrote.

“Cutting defense by over $1 trillion during a time of war with uncertainty in the Middle East is the wrong course of action.

“While I fully support actions to reduce the $16 trillion national debt and the budget cuts and reforms that are needed, we cannot place half the burden of such cuts on the men and women in uniform.”

The governor reminded the president that Secretary of Defense Leon Panetta said the cuts would “have a devastating effect not only on national defense, but I think on the rest of the country.”

“While the secretary has firmly condemned these massive defense cuts, we have not seen action yet from you to introduce a plan to reduce these cuts and support the Defense Department,” McDonnell wrote.

In his letter, McDonnell also cited a study by George Mason University economist Stephen Fuller on the effects of sequestration in Virginia.

Sequestration would cost the state 136,191 Defense Department and 71,380 additional jobs, more than $20.87 billion in gross state product, and more than $10.62 billion in labor income, Fuller’s study found.

McDonnell also pressed how the automatic cuts would affect aerospace and defense contractors; Virginia is one of the top 10 states for those industries, he wrote.

Many of those jobs are located in North Suffolk, known in military circles as “Pentagon South.”

“Uncertainty is pervasive in the defense industry, and at the direction of your administration, WARN Act notices” — a requirement to notify employees of impending redundancy — “have not gone out to advise Virginians of impending massive layoffs,” McDonnell wrote.

A memorandum issued by the Obama administration at the end of September stated the U.S. Labor Department concluded that “it is neither necessary or appropriate” for federal contractors to issue WARN Act notices in advance of the potential sequestration, and that litigation costs would be paid by contracting agencies.

The assurance is “of questionable authority,” McDonnell wrote, adding, “I join my fellow governors in red and blue states in urging you to bring the congressional leadership together to enact necessary legislation to avoid the disastrous effects of this policy.”