WASHINGTON — Fresh off becoming President Donald Trump’s first cabinet nominee to be confirmed, Secretary of State Marco Rubio embarked on his first day as America’s top diplomat on Tuesday, hosting a trio of counterparts from so-called Quad nations and laying out his vision for U.S. foreign policy under his guidance. 

After being sworn in by Vice President JD Vance in the morning, the new secretary and former Florida senator officially took his place at the helm of the influential State Department — one at the center of America’s foreign relations — in the afternoon when he delivered welcome remarks to employees. 

Rubio pledged that his mission, as directed by Trump, is to carry out a global policy agenda that puts the national interests of the U.S. first.

“That will be our job around the world – ensure that we have a foreign policy that advances the national interest of the United States,” Rubio said. 

He added that the “overriding goal” of U.S. foreign policy under his and Trump’s leadership will be the promotion of peace and avoidance of conflict. 

“No agency will be more critical in that regard than this one,” he said. 

At the same time, Rubio acknowledged significant challenges on the world stage, saying that in dealing with foreign relations there are often no good options and calling his role a “tough job.” 

”There will be conflicts,” Rubio said. “We will seek to prevent them and avoid them but never at the expense of our national interests.” 

The secretary also noted that there will be changes in the department in order to make it a “21st century agency” that can move “faster than we ever have.” He did not elaborate on such changes but added that the world is changing faster than ever before and the department needs to be operating with where things will stand in the years ahead in mind. 

”I want the Department of State to be at the center of how America engages the world — not just how we execute on it but how we formulate it,” he said. 

Rubio spent the rest of the afternoon sitting down with his counterparts from Japan, Australia and India — the three countries that, along with the U.S., make up the so-called Quad. The alliance — which represents nearly two billion people and more than a third of global GDP— was established in 2007 and has recently become an essential part of America’s approach to the Indo-Pacific, particularly as it looks to counter China’s growing assertiveness and vast territorial claims in the region. 

Not long after its founding, the Quad fell dormant and stayed that way for a decade until President Donald Trump in his first term agreed with the leaders of Japan, Australia and India to revive it.

Former President Joe Biden, who just left office on Monday, put a significant emphasis on the group and the Indo-Pacific region. He hosted the leader of each of the Quad countries for individual state visits fit with official glitzy dinners. All three leaders came to his personal home in Delaware for a summit. 

For his part, Rubio called China “the most potent, dangerous and near-peer adversary this nation has ever confronted” during his confirmation hearing last week and said the issues that gave rise to the rebirth of the Quad in Trump’s first term have only intensified.

Rubio, who was widely expected to be the Trump cabinet nominee with some of the least trouble getting through confirmation, received the unanimous backing of his senate colleagues on Monday night to officially secure the role. 

The Associated Press contributed to this report.