President Barack Obama and Israeli Prime Minister Benjamin Netanyahu are to meet in Washington next week, amid global concerns about Iran's nuclear program and possible pre-emptive action by Israel.
Tensions between Iran and Israel have increased steadily in recent months, as has speculation about a possible Israeli strike against Iran's nuclear sites. An Iranian general warned that Iran might strike first if threatened with an attack.
Potential war between a key U.S. ally and Iran, and its regional and global repercussions, is a major concern for U.S. President Barack Obama.
In his State of the Union Address in January, he urged Iranian leaders to change direction, but made clear the United States will defend not only its interests, but those of its allies.
"We will safeguard America’s own security against those who threaten our citizens, our friends, and our interests," the president said.
Iran -- which says its nuclear program is only for peaceful purposes -- recently denied International Atomic Energy Agency inspectors permission to visit a key military site.
White House Press Secretary Jay Carney said that was another demonstration that Iran is not yet changing direction.
"This particular action by Iran suggests that they have not changed their behavior when it comes to abiding by their international obligation," Carney said.
Debate has been intense about Iran's nuclear intentions, and the risks and repercussions of any pre-emptive strike. Ephraim Sneh, a former Israeli defense official, spoke recently at the Wilson International Center for Scholars.
"They crossed the threshold of enrichment to a point that they are a very short distance from a bomb," Sneh said.
But retired Admiral William Fallon, a former head of the U.S. Central Command, says Iran's actual intentions remain murky.
"Exactly what their intentions are, how far they have gone, whether they would actually if they had the means weaponize some nuclear capability. I think it remains to be seen," Fallon said.
A succession of U.S. officials have visited Israel, including General Martin Dempsey, the top U.S. military official. All reportedly urged Israeli Prime Minister Benjamin Netanyahu and other leaders to allow more time for sanctions against Iran to work.
Colin Kahl is an Associate Professor at the Georgetown University School of Foreign Service and a Senior Fellow at the Center for a New American Security
“In essence it is a game of time. The United States is trying to buy time for a diplomatic solution, some argue that the Iranians are trying to buy time to stall to make more and more nuclear progress,” Kahl said.
Other key Israeli officials, including Defense Minister Ehud Barak and President Shimon Peres, have also visited Washington recently, to lay the groundwork for Monday's Obama-Netanyahu talks.