Defense Secretary Ash Carter is departing as President Barack Obama's top defense advisor after nearly two years in the post, during which he led initiatives to modernize and strengthen the department while confronting myriad global challenges in a changing strategic landscape.
"America is today the world’s foremost leader, partner and underwriter of stability and security in every region across the globe, as it has been since the end of World War II," Carter said Jan. 9 in his Cabinet exit memo.
But even as the United States continues to fulfill that role, it is evident, Carter said, that the nation is facing a new strategic era.
"Today’s security environment is dramatically different -- more diverse and complex in the scope of its challenges – than the one we’ve been engaged with for the last 25 years, and it requires new ways of thinking and new ways of acting," he said.
Carter was sworn in Feb. 17, 2015, as the 25th secretary of defense. A physicist with nearly 35 years of government service, he previously served as deputy defense secretary and as undersecretary of defense for acquisition, technology and logistics.
"It has been the highest honor of my lifetime to lead this great department and to serve the American people," said Carter, who leaves his post today.
President-elect Donald J. Trump has selected retired Marine Corps Gen. James N. Mattis, pending Senate confirmation, to succeed Carter as defense secretary, charged with leading the agency of 2 million service members and 700,000 civilians who serve around the globe.
'Greatest Fighting Force'
U.S. military personnel are deployed worldwide addressing the nation’s security priorities, including providing reassurance to allies in Eastern Europe amid the threat of Russian aggression, advising and assisting security forces in Afghanistan, strengthening alliances in the Asia-Pacific region, standing ready in South Korea, and conducting strikes and supporting local partners in the fight against the Islamic State of Iraq and the Levant in Iraq, Syria and elsewhere.
Carter has traveled extensively throughout the world to see these efforts firsthand, engage with his global counterparts and thank service members.
"Our men and women in uniform without a doubt represent the greatest fighting force the world has ever known," he said in his exit memo, adding, "I am mindful every moment of the day that they are carrying out their noble mission in each and every time zone of the globe."
No matter what the challenge, one thing is certain Carter said: "America’s men and women in uniform stand ready to meet the challenges of today and tomorrow, whatever they might be."
Five Evolving Global Challenges
Carter has highlighted five "major, unique, and rapidly evolving challenges" the nation faces: Chinese aggression in the South China Sea; Russian aggression in Eastern Europe; North Korean nuclear and missile provocations; Iranian aggression and malign influence in the Gulf; and global terrorism, including ISIL.
"We don’t have the luxury of choosing among these challenges – we have to address them all," he said. "At the same time, we must contend with an uncertain future – ensuring that we continue to be ready for challenges we may not anticipate."
'Certain and Lasting Defeat' of ISIL
The United States and coalition forces continue to make significant gains against ISIL, through strikes against terrorist targets and supporting local forces on the ground in Iraq, Syria and elsewhere.
"We’re conducting an aggressive global campaign against terrorists and other violent extremists," Carter said, noting the efforts are "accelerating the certain and lasting defeat" of ISIL while protecting the United States and its people.
Rebalance to the Pacific
During Carter's tenure, the United States remained focused on its rebalance to the Asia-Pacific region, with strengthening and modernizing alliances a priority for security interests and sustaining U.S. global leadership.
The United States has supported security and stability in the Asia-Pacific region for 70 years, Carter said, noting that it’s an area of immense economic and strategic interest and is home to nearly half the world's population and nearly half the global economy.
The Defense Department has increased investments in capabilities and technologies, while positioning 60 percent of its Navy and overseas Air Force assets in the Asia-Pacific region, including some of its most advanced capabilities.
"We’re managing historic change in the Asia-Pacific – the single most consequential region for America’s future," he said.
Carter has worked to reassure European allies about the U.S. commitment to the defense of its NATO allies and to counter "the prospect of Russian aggression and coercion, especially in Europe."
The United States has increased joint multinational exercises and supports enhanced U.S. force posture through rotational deployments, pre-positioning of equipment and materiel, and further developing the capability of NATO allies and partners.
"The United States must remain engaged with NATO – an alliance of principled and like-minded members backed by strength – to ensure continued progress and to deter and defend against Russian aggression in Europe," Carter said.
North Korea, Iran
In the face of North Korea’s continued nuclear and missile provocations, the United States is improving its nuclear and conventional deterrent capabilities, Carter said. Thousands of U.S. troops in South Korea are ready to "fight tonight" if called upon.
In addition, he said, the Defense Department is "checking Iranian aggression and malign influence in the Gulf" and protecting friends and allies in the Middle East.
Force of the Future
Carter has led initiatives to modernize the Defense Department, incorporate cutting-edge technology, improve readiness, and attract and maintain the best talent for the all-volunteer force.
He sought to incorporate the best practices from the private sector through Defense Innovation Unit Experimental, or DIUx, which does business "outside the traditional defense orbit." In addition, the Defense Digital Service brings in talent from the private tech world for a time to help the department solve complex problems.
Carter has encouraged defense personnel to "think outside the five-sided box" as he sought to build bridges with Silicon Valley and the tech community. Initiatives include "Hack the Pentagon," where vetted computer users were invited to find vulnerabilities in public-facing DoD websites.
Remaining the best requires the best of technology, agility, full-spectrum readiness and innovative war plans, according to Carter. The department need to be superior not only in not only in the domains of land, air, and sea, but also in space and cyberspace, in this rapidly changing, uncertain and highly competitive world.
But, Carter has underscored the most important aspect in remaining the best: recruiting, retaining, and developing the people -- uniformed and civilian – who will make up the force of the future.
Strengthening All-Volunteer Force
As part of efforts to strengthen the all-volunteer force, Carter announced Dec. 3, 2015, that he had ordered the opening of all military occupations to women, including combat positions. Women have already seen combat in Iraq and Afghanistan -- serving, fighting and, in some cases, making the ultimate sacrifice, he said at the Pentagon announcement.
It made sense -- and was backed by years of study -- to open all military occupations to women, he explained.
In addition to women now being able to serve as Army Rangers, Navy SEALs, Marine Corps infantry members and Air Force pararescue airmen, the military "will be better able to harness the skills and perspectives that talented women have to offer," Carter said.
The military has long prided itself on being a meritocracy, where those who serve are judged not on who they are, but rather on what they can contribute, he said.
"That's why we have the finest fighting force the world has ever known," he said. "It's one other way we will strive to ensure that the force of the future remains long into the future." In another step of inclusion, the department last year lifted its ban on transgender service members.
The decisions to open all jobs to women and to lift the ban on transgender service members were made with the "goal of being able to draw from 100 percent of America’s population for our all-volunteer force, focusing purely on a person’s willingness and ability to serve our country and contribute to our mission," Carter said Nov. 1, 2016, in a speech in New York.
Enduring Confidence in Military
Just as it has always done, the United States military will remain focused on its most sacred duty of protecting the American people, Carter said.
"While the next administration will continue to be challenged by an evolving security environment, I am confident that our military is up to the task of protecting our nation in the years ahead," he said in his exit memo.
(Follow Lisa Ferdinando on Twitter: @FerdinandoDoD)