WASHINGTON (AFP) - President Barack Obama's pick to lead the Pentagon, Chuck Hagel, told senators Thursday he would not hesitate to use "the full force of the United States military" to defend America's security.

Seeking to counter accusations from some lawmakers that he is ready to appease US adversaries, Hagel said at his confirmation hearing that he wanted to keep America's armed forces the strongest in the world and was prepared to back military action when necessary.

"We will not hesitate to use the full force of the United States military in defence of our security," Hagel said in an opening statement before the Senate Armed Services Committee.

"But we must also be smart, and more importantly wise, in how we employ all of our nation's great power." Hagel, who was wounded and decorated for his combat tour with an infantry unit in Vietnam, broke ranks with his fellow Republicans over the Iraq war and has come under fire for some statements and senate votes on Israel and Iran.

The blunt-speaking former senator from Nebraska has said military action should be a last resort and has sometimes expressed impatience with Israel while expressing support for direct talks with Iran over its nuclear programme.

But Hagel has pursued a charm offensive in recent weeks, seeking to allay concerns of some Republicans and Democrats in a flurry of meetings.

In his opening statement, he told the committee that "no one individual vote, quote or statement defines me, my beliefs, or my record."

"My overall worldview has never changed: that America has and must maintain the strongest military in the world; that we must lead the international community to confront threats and challenges together; and that we must use all tools of American power to protect our citizens and our interests."

Some Republican lawmakers have also accused Hagel of being too soft on arms control and criticised his support for scaling back the country's nuclear arsenal.