As part of his quest to "put America first," President Trump is requesting a $55 billion increase in the Defense Department budget at the expense of agencies typically characterized as "non-defense": The Department of State and the Agency for International Development (USAID) face reductions of approximately 20 percent.

Trump has a misguided notion of defense. The State Department and USAID are recognized by defense leaders as irreplaceable components of our national security bulwark. Slashing the budgets of the diplomacy, aid and development agencies will create new threats to national security, diminish our international influence, harm American workers and the American economy.

Soft power is not a feeble notion. It is accepted fact at the highest levels of our military. Defense Secretary James "Mad Dog" Mattis once warned Congress that "if you don't fund the State Department fully, then I need to buy more ammunition...the more that we put into the State Department's diplomacy, hopefully the less we have to put into a military budget as we deal with the outcome of an apparent American withdrawal from the international scene."

Over 120 retired generals and admirals have jointly called on Congress to reject Trump's naïve proposal. "Development agencies are critical to preventing conflict and reducing the need to put our men and women in uniform in harm's way," they wrote.

Having served in the Foreign Service for 38 years, from the consulate level all the way to Assistant Secretary of State, I can attest to the value of a highly-qualified corps of professional diplomats and their loyal staffs of American and foreign nationals. Career Foreign Service professionals, serving in over 200 US embassies and consulates in virtually every country in the world, are the global eyes and ears of the President, the government and the American people. Plugging our ears and turning away from the world will only make it more difficult for the military and the U.S. government to defend our interests.

In any case, foreign affairs spending accounts for less than one percent of the overall federal budget, practically a drop in the bucket. The program cost of several of the military's new weapons systems, on their own, amounts to more than a dozen times the entire State Department budget.

Even relief and development aid to needy regions, which may seem like a sort of "handout," in fact contributes to the U.S. economy while minimizing the need for American military intervention. U.S. aid to Africa - a frequent target of foreign aid naysayers - is smart money. It promotes stable governments that reject dangerous militant and terrorist groups, grows a middle class and economies ripe for American investment and products. It also prevents the global spread of infectious diseases like Ebola.

The "Power Africa" electrification program, for instance, is essentially a private investment campaign enlisting American workers and businesses. The CBO says the program will save taxpayers $86 million over a five-year period, which is a likely reason it enjoys broad bipartisan support. Indeed, our aid and diplomatic relations with Africa have traditionally been a nonpartisan issue. If Trump is serious about reducing government spending, slashing this program would be counterproductive.

But beyond their security, economic, and humanitarian results, diplomacy and aid programs foster something equally important, yet less tangible: a growing confidence in America and its values. Turning off U.S. assistance means foreign leaders will look to our geopolitical adversaries, serving their interests and adopting their corrupted morals.

Converting diplomacy dollars into weaponry will only make our nation less safe in a less-secure world. I urge the President and Congress to listen those of us from the diplomatic and military communities who warn of dire long-term consequences. Slashing the diplomacy and foreign aid budgets will cost us more than it saves.

Herman J. Cohen was the United States Assistant Secretary of State for African Affairs from 1989 to 1993. He is the author of The Mind of the African Strongman: Conversations with Dictators, Statesmen, and Father Figures.