This section of the list is not an endorsement of the theories of the authors, but works of literature that will help one understand international relations, geopolitics, and foreign policy greatly.
The Prince by Niccolo Machiavelli
The History of the Peloponnesian War by Thucydides
Strategy: The Logic of War and Peace by Edward Luttwak
Democracy in America by Alexis de Tocqueville
Diplomacy by Henry Kissinger
World Order by Henry Kissinger
Introduction to International Relations by Robert Jackson
International Political Economy Paperback by Thomas Oatley
End of History by Francis Fukuyama
Identity by Francis Fukuyama
This section contains many core works of literature that explain Neoconservatism in an accessible way.
The Neoconservative Persuasion by Irving Kristol
If you read just one of the books on this list, make it this one.
Dangerous Nation by Robert Kagan
The World America Made by Robert Kagan
Why the World Needs a Powerful America by Dick Cheney
Suicide of the West by Jonah Goldberg
The Big Stick by Elliot Cohen
Neoconservatism: Why We Need It by Douglas Murray
In Defence of the Bush Doctrine by Robert Kaufman
These texts are more advanced readings that will require a good grasp of geopolitics, international relations, history, and political philosophy to understand.
The Political Philosophy of Hobbes: Its Basis and Its Genesis by Leo Strauss
Natural Right and History by Leo Strauss
Other good books that will help shape an understanding of the aforementioned fields and neoconservatism.
The Last Lion: Winston Spencer Churchill by William Manchester
Wilson by A Scott Berg
Cultural Realism: Strategic Culture and Grand Strategy in Chinese History by Alastair Iain Johnston
Mughal Warfare by Jos Gommans
Grand Strategy of the Habsburg Empire by A. Wess Mitchell
The Retreat of Western Liberalism by Edward Luce
Other literature I enjoyed
This section simply includes books I've read in the past that I found quite enjoyable to read or illuminating.
How the Catholic Church Built Western Civilization by Thomas E. Woods
The Protestant Ethic and the Spirit of Capitalism by Max Weber
Excuse Me, Professor: Challenging the Myths of Progressivism by Lawrence Reed
Capital in the 21st Century by Thomas Pikkety
The Problem of Pain by CS Lewis
Longing for the Lost Caliphate: A Transregional History by Mona Hassan
The Story of the Qur'an: Its History and Place in Muslim Life by Ingrid Mattson