President-elect Barack Obama takes questions from reporters during a news conference in Chicago, Monday, Dec. 1, 2008, with, from left to right: Attorney General-designate Eric Holder; Homeland Security Secretary-designate Janet Napolitano; Defense Secretary Robert Gates; Vice President-elect Joe Biden; Secretary of State-designate Sen. Hillary Rodham Clinton, D-N.Y.; National Security Adviser-designate Ret. Marine Gen. James Jones; and United Nations Ambassador-designate Susan Rice.

U.S. Democratic presidential nominee Barack Obama (R) and Senator Hillary Rodham Clinton attend a money raising meeting in New York, the United States, in this file photo taken on July 10, 2008. U.S. President-elect Barack Obama nominated Senator Hillary Rodham Clinton for Secretary of State at a news conference in Chicago on Monday.

U.S. President-elect Barack Obama (R) stands with his national security team nominees Eric Holder (Attorney General), Arizona Governor Janet Napolitano (Head of Homeland Security), Robert Gates (continuing as Secretary of Defense), Vice President-elect Joe Biden, Senator Hillary Clinton (Secretary of State), retired Marine General James Jones (National Security Advisor) and Susan Rice (U.S. Ambassador to the United Nations) (L-R) during a news conference in Chicago December 1, 2008.

WASHINGTON, Dec. 1 (Xinhua) -- U.S. President-elect Barack Obama announced on Monday his national security team, including former first lady Hillary Rodham Clinton as secretary of states and incumbent Defense Secretary Robert Gates, who would retain his post.

"America must be strong at home and abroad," Obama told a news conference in his transition office headquarters in Chicago, Illinois, drawing a full stop to a month-long speculations on his cabinet members.

"To succeed, we must pursue a new strategy that power: our military and diplomacy, our intelligence and law enforcement, our economy and the power of our moral example," said the president-elect with all national security team members announced standing beside him.

"They share my pragmatism about the use of power, and my sense of purpose about America's role as a leader in the world," he said.

Obama referred his former presidential rival Clinton as "a friend, a colleague, a source of counsel and as a campaign opponent" who possesses "an extraordinary intelligence and toughness."

Clinton's appointment to the top diplomatic official, as Obama said, is "a sign to friend and foe of the seriousness of my commitment to renew American diplomacy and restore our alliance."

Echoing Obama's remarks, Clinton told the press conference that she would make the United States a new force for positive change and work with the global community to solve crises around the world.

"The American people have demanded not just a new direction at home, but a new effort to renew America's standing in the world as a force for positive change," she said after being nominated.

Gates, the political independent who was nominated by the Republican government led by President George W. Bush as the defense chief, became the only current cabinet member who would retain his post.

"He earned the respect of members of Congress on both sides of the aisle for his pragmatism and competence," Obama said of his choice for the Pentagon chief. "He knows that we need a sustainable national security strategy -- and that includes a bipartisan consensus at home."

In a brief presentation, Gates vowed to do his duties as the country is engaging in two wars and said he is honored to "continue to serve our country" and "will be honored to serve President-elect Obama."

Obama also named retired Marine Gen. Jim Jones as his White House national security advisor and Susan Rice as the next U.S. Ambassador to the United Nations.

Jones, the only Republican who has been officially recruited to the next cabinet, was described by Obama as the one "uniquely suited to be a strong and skilled national security advisor" due to his understanding of "the connection between energy and national security" and experience in working on the frontlines of global instability.

Obama settled his long-term closest advisor Rice in the UN for her knowledge that the global challenges the U.S. face demand global institutions.

The former assistant secretary of state for African affairs noted that the United States "must invest in our common humanity" to accomplish America's security with help of "capable partners and effective international institutions."

The team, also including Arizona governor Janet Napolitano as the homeland security secretary and Eric Holder as the next attorney general.

Holder, as the first African-American head of Justice Department, promised to revitalize the department that has been haunted by scandals during Bush's administration, and make sure "American people remain secure and that the great constitutional guarantees that define us as a nation are truly valued."

To lead the second biggest department comprising 170,000 staff from 22 federal agencies, Napolitano focused her future job on "protecting our homeland with constant vigilance and relentless work to prevent terrorist attacks" and planning "carefully and thorough" on the country's domestic response to all hazards.

It was the second batch of key cabinet members Obama has released since his successful presidential election after he presented the economic team last week.

The new administration will take office on Jan. 20 as Obama is sworn in to the White House as the 44th U.S. president.