A nuclear-armed Iran would threaten Israel’s existence, the security of the Persian Gulf nations, and global economic stability, President Barack Obama said Tuesday in his speech to the UN General Assembly.

"We respect the right of nations to access peaceful nuclear power. But one of the purposes of the United Nations is to see that we harness that power for peace," Obama told UN delegates. "Make no mistake: A nuclear-armed Iran is not a challenge that can be contained."

Obama also told the General Assembly that “the United States will do what we must to prevent Iran from obtaining a nuclear weapon.”

Obama’s comments came just a day after Iranian President Mahmoud Ahmadinejad made incendiary statements concerning Israel, saying it has “no roots” in the Middle East. Ahmadinejad is set to address the UN General Assembly on Wednesday.

Iran has insisted its nuclear program is strictly for peaceful purposes.

Israeli Prime Minister Benjamin Netanyahu has stepped up pressure on the United States in recent weeks to take a hard line to stem Iran’s nuclear ambitions.