The Pentagon's new chief hosted Israeli Defense Minister Ehud Barak on Tuesday for talks after having faced allegations from some US senators that he was too critical of the Jewish state.

For his first meeting with a foreign counterpart, Defense Secretary Chuck Hagel, who was sworn in last week, chose to meet Barak, apparently in a bid to reassure America's ally and its advocates in Washington over his stance towards Israel.

Hagel greeted Barak on the steps of the Pentagon entrance before an honor guard shortly after 10 am local time (1500 GMT), giving the Israeli minister an informal salute.

The two embraced and then walked into the building for discussions that are expected to focus on Iran's nuclear program, Syria's raging civil war and President Barack Obama's planned visit to Israel later this month.

Officials said no joint press conference was planned after the discussions between Hagel and Barak, who were to be joined by the US military's top officer, General Martin Dempsey and the Israeli ambassador to the US, Michael Oren.

Hagel, an ex-senator from Nebraska and Vietnam veteran, came under fierce criticism from his Republican former colleagues during his nomination process, with lawmakers painting him as hostile to Israel and naive on his views towards Iran.

During his confirmation hearing, Hagel rejected the criticism as inaccurate, but failed to persuade the Republican minority in the Senate. His nomination was approved in a narrow vote, 58-41, that saw most Republicans opposing Hagel for the job.

The meeting comes after both Barak and Israeli Prime Minister Benjamin Netanyahu addressed a session this week of the influential pro-Israel lobbying group, the American Israel Public Affairs Committee.

Netanyahu told the group Iran's nuclear program was moving closer to crossing a crucial "red line," conveying his impatience with an international effort to rely on sanctions to thwart Tehran's atomic ambitions.

Barak, speaking to the AIPAC conference on Sunday, warned that Israel would never allow Iranian leaders to develop a nuclear weapon.

Referring to military action, he said that "all options must remain on the table."

And Barak added: "We expect all those who say it to mean it. Ladies and gentlemen, we mean it. And let me repeat it, we mean it."

Obama and Netanyahu have had an uneasy relationship, marked by disagreement about how to counter Iran's sensitive uranium enrichment work.

The White House has argued that more time is needed to allow tough economic sanctions to take effect while Israeli officials have insisted the window for potential military action will soon close.

Obama is due to make his first trip as president to Israel in two weeks' time.