Republican presidential nominee former President Donald Trump greets Sen. Marco Rubio, R-Fla., during a campaign rally at J.S. Dorton Arena, Nov. 4, in Raleigh, N.C. (AP)

US President-elect Donald Trump officially nominated Florida Sen. Marco Rubio as his secretary of state on Wednesday, calling him a "strong advocate for our nation" and a "true friend to our allies."

Trump issued a statement on the nomination of Rubio, known for his hawkish stance on China and Iran, as America's next top diplomat is to face a full plate of foreign policy challenges, including an intensifying rivalry with China, Russia's war in Ukraine and North Korea's evolving security threats to name a few.

"It is my Great Honor to announce that Senator Marco Rubio of Florida is hereby nominated to be The United States Secretary of State," Trump wrote in the statement.

"Marco is a Highly Respected Leader, and a very powerful Voice for Freedom. He will be a strong Advocate for our Nation, a true friend to our Allies, and a fearless Warrior who will never back down to our adversaries. I look forward to working with Marco to Make America, and the World, Safe and Great Again!," he added.

Rubio is expected to have a hard-line stance on North Korea's deepening security challenge. His interview with CBS News in 2017 gave a glimpse into his thoughts about Pyongyang's military threats, particularly its intercontinental ballistic missile capabilities.

"We must do almost whatever it takes, just about anything, to prevent Kim Jong-un from acquiring the nuclear capability he can deliver against the mainland of the United States of America," Rubio said in the interview, referring to the North Korean leader.

Rubio is also said to have a grasp of the security situation on the Korean Peninsula as he has visited the heavily fortified Demilitarized Zone separating the two Koreas before.

Born in 1971 as the son of two Cuban immigrants, he graduated from the University of Florida and the University of Miami Law School. Rubio served as a city commissioner in West Miami and speaker of the Florida House of Representatives. In 2010, he won a seat in the Senate.

With the nomination of Rubio, Trump has all but completed the formation of his foreign policy and security team.

On Tuesday, Trump tapped Florida Rep. Mike Waltz, a Green Beret veteran, as his national security adviser. He is known as a China hawk, having called for a full US boycott of the Beijing 2022 Winter Olympics and maintaining a hard-line stance on human rights issues in China.

On the same day, the president-elect named Fox News Channel host Pete Hegseth to serve as his defense secretary. Hegseth is an Army veteran with tours in Guantanamo Bay, Iraq and Afghanistan. He also nominated former Director of National Intelligence (DNI) John Ratcliffe as his pick to lead the Central Intelligence Agency.

For the DNI post, Trump named former congresswoman Tulsi Gabbard on Wednesday.