Hillary Clinton has appeared before the US Senate Committee on Foreign Relations to be confirmed as the next Secretary of State.
The Senator from New York and former first lady received a warm reception on Tuesday from her former colleagues.
A vote on her nomination is scheduled for Thursday.
Mrs Clinton said the United States must address Israel's security needs while at the same time tackle the "legitimate" political and economic aspirations of the Palestinians.
She said the United States must effectively challenge Iran to end its nuclear weapons programme and convince both Tehran and Syria to "abandon their dangerous behavior and become constructive regional actors."
Mrs Clinton also ruled out negotiations with the Hamas until it recognises Israel and abandons violence.
She also backed the six-party talks on ending North Korea's nuclear ambitions. The talks include both North and South Korea, China, Japan, Russia and the United States.
Under the six-party talks, North Korea in 2005 agreed to abandon all its nuclear programmes. However, Pyongyang tested a nuclear device in 2006 and has been slow to implement agreements on disabling its plutonium programme.
Mrs Clinton said she would focus on the Darfur crisis and the incoming administration was looking at options including the creation of no-fly zones.
She told the hearing that Darfur "is a terrible humanitarian crisis compounded by a corrupt and very cruel regime in Khartoum."
Foreign policy experts say 200,000 people have died and 2.5 million driven from their homes in five years of fighting between rebels and the army and government-backed militias.
Khartoum accuses Western media of exaggerating the death toll.