Condoleezza Rice, President George W Bush's nominee as secretary of state, says she will strengthen US ties with allies through diplomacy.
Rice will have to unveil her own vision of the world
"Our interaction with the rest of the world must be a conversation, not a monologue," Ms Rice told a US Senate committee at her confirmation hearing.
Tuesday's session mainly focused on eliciting answers on US policy on Iraq.
If confirmed as expected, Ms Rice, 50, will be the first black woman to hold the office of US secretary of state.
The hearing may last until Wednesday - a day before Mr Bush is sworn in for his second term.
Senators at the committee have been asking Ms Rice detailed questions to elicit her own opinions and judgements, primarily on Iraq.
And one in particular - Senator John Kerry who lost the presidential race to Mr Bush - said he was concerned by Ms Rice's answers, including the number of troops needed for the Iraq operations.
To no-one's great surprise Ms Rice had little to add to what is currently known about administration policy in Iraq, says the BBC's Justin Webb in Washington.
"We must use American diplomacy to help create a balance of power in the world that favours freedom," Ms Rice told the Senate Foreign Relations Committee.
"And the time for diplomacy is now."
She praised the leadership of President Bush in the aftermath of the 11 September 2001 attacks - "a defining moment for our nation and the world".
"Under the vision and leadership of President Bush," she said, "our nation has risen to meet the challenges of our time: fighting tyranny and terror, and securing the blessings of freedom and prosperity for a new generation."
"Now is the time to build on these achievements to make the world safer, and to make the world more free," she said.
But she indicated that the US would not let traditional allies or multilateral institutions stand in the way of "effective" action by Washington.
"The time for diplomacy is long overdue," said Senator Joseph Biden, a Democrat. He said the US was "paying a heavy price" for the administration's policy in Iraq - the focus of most of Tuesday's questioning.
Senators were particularly interested to know whether the US had enough troops in Iraq and whether it had an exit strategy. Ms Rice said the US had to remain engaged after the Iraqi election on 30 January including improving the Iraqis' ability to defend themselves.
On other foreign policy issues, Ms Rice said:
RECENT SECRETARIES OF STATE
Colin Powell: 2001-2004
Madeleine Albright: 1997-2001
Warren Christopher: 1993-1997
James Baker: 1989-1992
George Schultz: 1982-1989
- "I look forward to personally working with Palestinian and Israeli leaders, and bringing American diplomacy to bear on this difficult but crucial issue
- "We must remain united in insisting that Iran and North Korea abandon their nuclear weapons
- "We are building a candid, co-operative and constructive relationship with China that embraces our common interests but still recognises our considerable differences about values."
Ms Rice is a trusted member of President's Bush innermost circle - some describe her as almost family, correspondents say.
She is also said to share many of his views, and is described as driven and highly ambitious.