(CN) — In announcing his slate of foreign policy and national security top officials, President-elect Joe Biden signaled a sharp divergence from Donald Trump’s “America First” policy and vowed to cooperate with allies, use diplomacy to check adversaries and prioritize the fight against climate change. 

“America is back, ready to lead the world, not retreat from it,” Biden said. 

Biden’s nomination for secretary of state, Antony Blinken, reiterated those sentiments during his brief remarks given at the Queen Theater in downtown Wilmington, Delaware. 

“We need to be working with other countries,” Blinkin said. “We need their cooperation and their partnership.”

Biden talked about the need to rebuild morale at the State Department, where many career diplomats reportedly felt sidelined during the Trump administration. 

“Tony starts off with the kind of relationships around the world that many have to build over the years,” Biden said. 

Blinken talked about his relatives’ decision to come to America, whether fleeing the pogroms of Russia in the early 20th century or the communist regime in Hungary later on. 

“For my family, as for so many generations of Americans, America has literally been the last best hope on Earth,” he said. 

Blinken’s remarks represent another sharp departure from the anti-immigration rhetoric that defined Trump’s initial campaign and some of his more divisive policy decisions while in office. 

Alejandro Mayorkas, Biden’s nomination to run the Department of Homeland Security, also pledged to honor America’s legacy as a bastion for refugees. 

“The Department of Homeland Security has a noble mission to keep us safe and advance our proud history as a country of welcome,” Mayorkas said. 

Mayorkas, the son of Cuban refugees who fled the Castro regime, will become the first Latino to run the department that oversees Immigration and Customs Enforcement.

Biden called the immigration system “broken” and said Mayorkas will have a critical role in fixing it. 

Biden also indirectly criticized Trump for selecting partisans and loyalists to fill out his cabinet. 

He said his nomination of Avril Haines, who will be the first female director of National Intelligence if confirmed, was done in part because he could trust her to tell him difficult but necessary truths. 

“I didn’t pick a politician, I picked a professional,” Biden said of Haines. 

Haines took her time at the podium to single out the work of the employees of America’s intelligence apparatus — also a departure from Trump’s practice of castigating members of the intelligence community as members of the so-called “deep state.” 

“To the intelligence officials, you work under some of the most austere conditions imaginable,” she said, adding they will need to continue to do so to combat cyberattacks, terrorism, the threat of nuclear proliferation and new threats like pandemics and climate change.

Former Secretary of State John Kerry’s presence on the stage attested to Biden’s emphasis on fighting climate change during his administration. 

“For the first time ever, the United States will have a full-time climate envoy with a seat at every table around the world,” Biden said, referring to the position he created for Kerry. “He will make sure the climate is on the agenda in the Situation Room.”

Kerry said it will take resolve, brainpower and a commitment to transitioning to renewable energy. 

“No one should underestimate the determination of this president,” Kerry said of Biden. “And they shouldn’t doubt the country that went to the moon, cured supposedly incurable diseases and beat global tyranny during World War II.” 

Jake Sullivan, one of the youngest National Security advisers ever at age 44, pledged to place working middle-class families at the center of his foreign policy recommendations. 

And Linda Thomas-Greenfield, the nominee to be ambassador the United Nations, once again pledged to represent an America that is reengaged with the world. 

“Diplomacy is back,” she said.