In a brief letter to employees,Tillerson said aid and U.S. engagement must become more efficient. (Franck Robichon/AP)

Secretary of State Rex Tillerson told agency employees in a letter Thursday morning that next year’s budget proposal, marked by deep funding cuts, is an “unmistakable restatement” of the country’s needs and a harbinger of new priorities.

The nine-sentence letter, emailed to State employees as Tillerson was traveling in Asia, came shortly after the administration released a blueprint of plans to cut more than $10 billion, or 28 percent, out of the core budget for the State Department and the U.S. Agency for International Development. If approved by Congress, the plan would slash foreign aid, eliminate contributions to international climate change funds and reduce many cultural and educational exchange programs.

At a brief news conference in Tokyo on Thursday, Tillerson said the current level of spending — more than $50 billion — was “simply not sustainable.”

The proposed budget would slice spending to $37.6 billion, including $12 billion for operations in war-torn areas. Tillerson said the lower budget reflects the administration’s expectations that the United States will be engaged in fewer foreign wars, and that other countries will contribute more to development and disaster aid.

(Jenny Starrs/The Washington Post)

He expanded on that theme in his letter to the State Department’s 75,000 employees.

“It acknowledges that U.S. engagement must be more efficient, that our aid be more effective, and that advocating the national interests of our country always be our primary mission,” he said of the budget proposal. “Additionally, the budget is an acknowledgment that development needs are a global challenge to be met not just by contributions from the United States, but through greater partnership with and contributions from our allies and others.”

Tillerson said that in coming weeks, the State Department will draft a new budget blueprint for spending in coming decades.

“We will do this by reviewing and selecting our priorities, using the available resources, and putting our people in a position to succeed,” he said. “We have a genuine opportunity to set a new course.”