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The United States has made "direct contact" with Iran to discuss the alleged Tehran-backed plot to assassinate the Saudi ambassador to Washington, the State Department said Thursday.

State Department spokeswoman Victoria Nuland, without saying who was involved in the talks, confirmed that the Obama administration has contacted Iran over the charges unveiled Tuesday.

"We have had direct contact with Iran. I'm not going to give you any further details than that," she told reporters.

The outreach comes as President Obama forcefully defends U.S. claims that the plot had "direct links" to the Iranian government.

Obama, in his first public remarks on the alleged plot, described the Iranian involvement Thursday as a "dangerous escalation" and said the international response will ensure the country "pays the price" for its behavior.

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"This is part of a pattern of dangerous and reckless behavior by the Iranian government," Obama said, in response to a question from Fox News.

He spoke about the alleged plot to kill the Saudi ambassador to the U.S. during a joint press conference with South Korean President Lee Myung-bak. During his remarks, Obama said there is a "great similarity" between the behavior of Iran and that of North Korea.

Obama did not go into specific detail about what the response to the plot might entail, but said it will start with the Justice Department-level prosecution over the plot and the application of the "toughest sanctions" toward Iran. He said the U.S. would continue to "mobilize" the international community to isolate Iran, predicting other nations will "punish Iran" for this decision.

"We don't take any options off the table," Obama said.

Iranian representatives have vigorously denied charges that the government was involved in the plot.

But Obama defended the veracity of the United States' claims, saying the suspect who's been arrested was "paid by and directed by individuals in the Iranian government." U.S. officials have previously said the special operations Quds Force was pulling the strings.

"Those facts are there for all to see," Obama said. "We would not be bringing forward a case unless we knew exactly how to support all the allegations that are contained in the indictment."

He did not mention any calls made from the U.S. to Iranian officials.

The president said U.S. officials have contacted allies to explain the case and predicted that after they analyze the facts, "there will not be a dispute that this is in fact what happened."