WASHINGTON — Iran’s leadership has shown itself more willing to carry out attacks on American soil, the U.S. intelligence chief told Congress.

“The 2011 plot  to assassinate the Saudi ambassador to the United States shows that some Iranian officials — probably including Supreme Leader Ali Khameini — have changed their calculus and are now more willing to conduct an attack in the United States in response to real or perceived U.S. actions that threaten the regime,” James Clapper, the director of national intelligence, told the Senate Select Committee on Intelligence in an unclassified written threat assessment delivered during the committee’s hearings on Tuesday.

The United States in recent months has led an international intensification of sanctions and also raised its military profile in the Persian Gulf. Clapper said Iran is “expanding its uranium enrichment capabilities,” strengthening the U.S. intelligence agencies’ assessment that “Iran has the scientific, technical and industrial capacity to eventually produce nuclear weapons.”

However, he also said that intelligence services “do not know” if Iran will eventually build nuclear weapons. The central issue, he said, is “its political will to do so.”

Clapper noted increased domestic unrest in Iran and infighting in its political elites.

He also said that “Iran’s economy is weighed down by international sanctions,” but added a caveat: “Despite this, Iran’s economic difficulties will probably not jeopardize the regime, absent a sudden and sustained fall in oil prices or a sudden domestic crisis that disrupts oil exports.”