Secretary of State Hillary Clinton denied Wednesday that the United States was involved in the assassination of an Iranian nuclear scientist.

“I want to categorically deny any United States involvement
in any kind of act of violence inside Iran,” Clinton said at a Wednesday news
conference.

{mosads}The assassination of Mostafa Ahmadi Roshan, who was deputy
director of an Iranian nuclear facility, was just the latest in a series of
escalations between Iran and the West in recent months.

According to Iran’s semiofficial Fars News Agency, Roshan
was killed after a motorcyclist planted a bomb under his car. A subsequent
report blamed Israel for the attack.

Tensions between Iran and the United States have been simmering long before Wednesday’s
attack. Iran threatened to close the Strait of Hormuz, a key oil passageway, in
response to economic sanctions over Iran’s nuclear program. Iran then warned that U.S. ships should
leave the Persian Gulf. Earlier this week Iran sentenced to death a former
U.S. Marine.

Clinton said Wednesday that Iran’s recent threats were “provocative
and dangerous.” The U.S. military has responded that it would not stop
operations in the gulf and would respond to any attempt to close the strait,
including with force.

Clinton reiterated that stand Wednesday.

“This is an international
waterway,” she said. “The U.S. and others are committed to keeping it open.
It’s part of the lifeline that keeps oil and gas moving around the world.”