I believe America’s role in the world is to advance the cause of a global middle class.

After more than 12 years on the battlefields of Iraq and Afghanistan, and after a global financial crisis that decimated our middle class, it is understandable that many Americans would like to disengage from the world. But our country’s security and prosperity demand that we be more engaged in the world, not less.

The first and foremost responsibility of the next Commander in Chief will be to keep America safe from 21st-century threats: violent extremism; nuclear proliferation; pandemics; cyberattacks; rising inequality; failed states; the mega-droughts, famines and floods caused by climate change; and more refugees than at any time since World War II.

We may have the most sophisticated military in history, but we do not have a silver bullet for these problems. So we must pursue a more collaborative, proactive, and farsighted foreign policy. We need new international partnerships to confront climate change and regional challenges, from the South China Sea to the sea lanes of the Middle East. We must create a new National Security Act to develop a broader framework for our national-security strategy. We must continue to adapt our military’s force structure and spending to meet today’s threats. And we must establish a cybersecurity unit in every state’s National Guard to better protect Americans’ personal data and critical infrastructure.

My vision for U.S. foreign policy focuses on the rise of a global middle class, which is a moral, economic, and national-security imperative. Eliminating the scourge of extreme poverty is a reflection of our most deeply held values. Supporting economic development will help us build the next generation of American political and economic partnerships. And protecting the dignity of human lives in fragile states will reduce the threat of being drawn into costly future conflicts.

We must also understand that comprehensive immigration reform is an economic and national-security interest. And we must forge a New Alliance for Progress based on shared interests in our own hemisphere, which we have neglected for too long. An early task should be to address the root causes of violence and instability in places like El Salvador and Honduras, heading off growing crises before they reach our borders.

We must listen to U.S. military leaders who have long recognized that climate change is a national security threat. Tackling the climate challenge will provide our nation the greatest business opportunity in 100 years. I strongly support an American Green Jobs Agenda. If we can put a man on the moon in a decade, we can power America with 100% renewable energy by 2050. It’s not the technology that’s lacking. It’s the political will.

All of this is within our reach. But it will require new leadership. Twitter and Facebook are no substitute for personal relationships and human intelligence. We must recruit a new generation of Americans to exercise our global economic, diplomatic, military, and healing power in ways consistent with our values. And we must give them the tools to engage a new generation of leaders abroad, often in hostile environments where we lack historic ties.

The cornerstone of American strength in the world is economic strength at home. Maintaining our security in the long run will require an economy that works for all Americans. No fighter jet or troop battalion will protect us as much as a vibrant economy. A stronger middle class is the first garrison against any threat we might face.

The greatest power we possess as Americans is not military might, but the power of our own example. We must lead the world by strengthening the American middle class and supporting the rise of a global middle class — free from want, and free from fear.

That will make us more prosperous and secure. That will give our children a better future with more opportunity. And that will make our planet healthier, more peaceful, and more just.

These are the foreign policy and national security goals worthy of a truly great people.

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