The U.S. Justice Department filed charges Tuesday against two Iranians, accusing them of conspiring with elements of the Iranian government to kill Saudi ambassador to the United States Adel al-Jubeir.

The White House says President Barack Obama called the Saudi ambassador to express solidarity against the plot, which he called a “flagrant violation” of U.S. and international law. The statement said the president is committed to protecting all diplomats serving in the United States, and also underscored the “close relationship” Saudi Arabia and the United States share.

Officials identified one suspect as Manssor Arbabsiar, a holder of Iranian and U.S. passports who was arrested at New York's John F. Kennedy International Airport on September 29.

The officials named the second suspect as Gholam Shakuri, an Iran-based member of the Iranian Quds force. They said Shakuri remains at large.

U.S. Attorney General Eric Holder told a news conference the plot was “conceived, sponsored and directed” from Iran. He said Washington will hold the Iranian government accountable.

Separately, U.S. Secretary of State Hillary Clinton told reporters the United States will work with its allies to send a “strong message” that such actions must stop.

She said the United States and its partners also will consider ways to “further isolate” Iran from the international community.

A White House spokesman said President Barack Obama was first briefed on the issue in June and directed his administration to provide all necessary support to the investigation. Mr. Obama praised the disruption of the alleged attack as a “significant achievement.”

Officials say Arbabsiar unknowingly hired an informant of the U.S. Drug Enforcement Administration to carry out the plot, believing the informant had ties to Mexican drug cartels capable of killing the Saudi ambassador. They say Arabsiar confessed to making a $100,000 down payment on the scheme with a price tag of $1.5 million.