“We possess weapons of tremendous power — but they are least effective in combating the weapons most often used by freedom's foes: subversion, infiltration, guerrilla warfare, civil disorder.”

Also quoted in "Warrior for Peace" by David Talbot, in TIME (2 July 2007), p. 50 http://www.time.com/time/specials/2007/article/0,28804,1635958_1635999_1634954-6,00.html
1961, Address at the University of Washington
Context: We increase our arms at a heavy cost, primarily to make certain that we will not have to use them. We must face up to the chance of war, if we are to maintain the peace. We must work with certain countries lacking in freedom in order to strengthen the cause of freedom. We find some who call themselves neutral who are our friends and sympathetic to us, and others who call themselves neutral who are unremittingly hostile to us. And as the most powerful defender of freedom on earth, we find ourselves unable to escape the responsibilities of freedom, and yet unable to exercise it without restraints imposed by the very freedoms we seek to protect. We cannot, as a free nation, compete with our adversaries in tactics of terror, assassination, false promises, counterfeit mobs and crises. We cannot, under the scrutiny of a free press and public, tell different stories to different audiences, foreign and domestic, friendly and hostile. We cannot abandon the slow processes of consulting with our allies to match the swift expediencies of those who merely dictate to their satellites. We can neither abandon nor control the international organization in which we now cast less than 1 percent of the vote in the General Assembly. We possess weapons of tremendous power — but they are least effective in combating the weapons most often used by freedom's foes: subversion, infiltration, guerrilla warfare, civil disorder. We send arms to other peoples — just as we send them the ideals of democracy in which we believe — but we cannot send them the will to use those arms or to abide by those ideals. And while we believe not only in the force of arms but in the force of right and reason, we have learned that reason does not always appeal to unreasonable men — that it is not always true that "a soft answer turneth away wrath" — and that right does not always make might. In short, we must face problems which do not lend themselves to easy or quick or permanent solutions. And we must face the fact that the United States is neither omnipotent or omniscient — that we are only 6 percent of the world's population — that we cannot impose our will upon the other 94 percent of mankind — that we cannot right every wrong or reverse each adversity — and that therefore there cannot be an American solution to every world problem.