Senior Obama administration officials say the U.S. does not have any information right now indicating that either Iranian Supreme Leader Ayatollah Ali Khamenei or President Mahmoud Ahmadinejad knew about the assassination plot against the Saudi ambassador to the U.S. that was revealed today.

But they underlined that absence of evidence was not necessarily evidence of absence. Meaning: Khamenei and Ahmadinejad might have known about the plot, there just isn’t yet any information to suggest that.

The assassination plot was tied to the Quds Force, the militant unit of Iran’s Army of the Guardians of the Islamic Revolution, which the U.S. government says has been tied to attacks on Americans in Iraq and Afghanistan, support for regimes in Syria and Lebanon, as well as support for Hamas and Hezbollah, which groups the U.S. State Department labels as terrorist.

“This plot is in keeping with their support for terrorism, but it escalates it,” a senior administration official told ABC News.

That a foreign government would plot to kill a foreign leader on American soil could be seen as an act of war, but Obama administration officials say the path the U.S. government will purse will align with American interests – and a military response and possible armed conflict with a third Muslim nation would not be part of that. (Though, it should be noted, the official White House position is “no option is off the table.”)

This afternoon the Treasury Department announced further sanctions against Iran, and in coming days diplomats at the United Nations and elsewhere will discuss further ways to isolate Iran, while American officials will spread far and wide throughout the region that the Iranian government was planning to kill an Arab leader.

The president was first briefed on the plot in June, and after law enforcement officials built enough of a case, the Saudi government was informed.

President Obama stopped by a “Principals Committee” meeting this morning at the White House – featuring Secretary of State Hillary Clinton, Secretary of Defense Leon Panetta, CIA director David Petreaus, National Security Adviser Tom Donilon, Attorney General Eric Holder, and others – to thank the team for its work and for preventing the assassination.

The Treasury Department this afternoon announced new sanctions on five individuals tied to the plot, four of whom are senior Quds Force officers:

· Qasem Soleimani, who oversees the Quds Force officers alleged to have been involved in this plot;

· Hamed Abdollahi, alleged to have coordinated aspects of this operation;

· Abdul Reza Shahlai alleged to have coordinated the assassination plot by working through his cousin Manssor Arbabsiar; and

· Ali Gholam Shakuri, alleged to have provided financial support to Arbabsiar as well as having met with him several times to discuss the planned assassination.

The fifth individual is Manssor Arbabsiar, accused of plotting to carry out the assassination of the Saudi ambassador.

Ahmadinejad has said he knew nothing about any plot, and he accused the U.S. of concocting the entire thing.

-Jake Tapper