At our best, being a great nation has always meant a commitment to building a better, safer world — not just for ourselves, but for our children and grandchildren. This has meant leading the world in advancing the cause of peace, responding when disease and disaster strike, lifting millions out of poverty and inspiring those yearning for freedom.

This calling is under threat.

The administration’s proposal, announced Tuesday, to slash approximately 30 percent from the State Department and foreign assistance budget signals an American retreat, leaving a vacuum that would make us far less safe and prosperous. While it may sound penny-wise, it is pound-foolish.

This proposal would bring resources for our civilian forces to a third of what we spent at the height of Ronald Reagan’s “peace through strength” years, as a percentage of the gross domestic product. It would be internationally irresponsible, distressing our friends, encouraging our enemies and undermining our own economic and national security interests.

The idea that putting Americans “first” requires a withdrawal from the world is simply wrongheaded, because a retreat would achieve exactly the opposite for our citizens. I learned that lesson the hard way when I became secretary of state after a decade of budget cuts that hollowed out our civilian foreign policy tools.