The White House said Monday that Iranian President Mahmoud Ahmadinejad's harsh criticisms of the United States, other Western powers, and Israel at a conference reviewing the Nuclear Non-Proliferation Treaty, or NPT, demonstrate Tehran's increasing isolation as it faces international pressure over its own nuclear ambitions.

At a White House press briefing, Spokesman Robert Gibbs called the Iranian president's remarks "predictable" in that the Tehran government continues to fail to speak about nonproliferation obligations that itself refuses to live up to.

American, British and French officials "rightly" walked out, said Gibbs, as the Iranian leader make a series of "wild accusations."

"Those that are involved in the NPT conference, that are living up to the obligations, would have wanted to hear the Iranians discuss living up to their obligations," said Robert Gibbs. "I think them not doing that again shows how further isolated they are from the world community. And we continue to make progress on sanctions at a multilateral level, even as we look at ways that we can do so within our own government."

The United States, Gibbs said, continues to work with other U.N. Security Council members, moving forward on developing a new sanctions resolution, but he offered no new details on this process.

At the end of a nuclear security summit he hosted in Washington last month, President Barack Obama said he knew negotiations could be difficult, but that he would push as hard as he could to ensure that a resolution contains strong sanctions with "consequences for Iran."

In his address at the NPT conference, the Iranian leader attacked the United States and Israel, saying the production, stockpiling of nuclear weapons or threats to use them is "for people characterized by a lack of consistent logic and behavior."

Responding to President Ahmadinejad, U.S. Secretary of State Hillary Clinton told the nonproliferation conference in New York that Iran has defied the U.N. Security Council and the International Atomic Energy Agency and placed the Nonproliferation Treaty in jeopardy.

Against the background of the Iranian president's attacks on Israel at the New York conference that the White House made a point on Monday of reiterating the strong U.S. commitment to Israel's security.

White House Press Secretary Gibbs told reporters that President Obama, during a 20 minute telephone conversation with Israeli Prime Minister Benjamin Netanyahu, reaffirmed his "unshakeable" commitment to Israel's security.