JERUSALEM/WASHINGTON - President Barack Obama told Israelis Iran is still more than year away from developing a nuclear weapon and sought to reassure them that military force remains a U.S. option if sanctions and diplomacy fail to thwart its nuclear ambitions.

In an interview with Israeli television broadcast on Thursday, just six days before his visit to the country, Obama appeared to send a message to Prime Minister Benjamin Netanyahu of the need for patience with Washington's Iran strategy while also showing U.S. resolve to confront Tehran if necessary.

Iran's nuclear standoff with the West will be high on the agenda during Obama's first presidential trip to the Jewish state, where he faces a tough challenge trying to narrow his differences on the matter with the right-wing prime minister.

Laying the groundwork for his talks with Netanyahu, Obama took the rare stsep of offering a U.S. assessment of how long it would take Iran to build a nuclear bomb should it make the final decision to pursue one. Tehran denies that is its aim.

"We think that it would take over a year or so for Iran to actually develop a nuclear weapon, but obviously we don't want to cut it too close," Obama said.

Netanyahu, at the United Nations in September, set a "red line" of spring or summer for when Iran would be close to weapons capability, suggesting prospects for an Israeli attack around that time. But Iran's latest talks with world powers plus adjustments in Tehran's uranium enrichment processes are widely thought to have pushed back that deadline.

Asked if he would order an attack on Iran should diplomacy fail, Obama said: "When I say that all options are on the table, all options are on the table."

"The United States obviously has significant capabilities but our goal here is to make sure that Iran does not possess a nuclear weapon that could threaten Israel or could trigger an arms race in the region," he said.

Obama and Netanyahu have had a notoriously fractious relationship, but with both leaders starting new terms they seem to have come to the realization that they are stuck with each other and have a chance to open a new chapter.

Outreach to Israeli public

Obama will also try a different tack, using his three-day visit to reach out to a wary Israeli public and try to convince them of his commitment to their security. The centerpiece will be a nationally televised address to university students in Jerusalem on Thursday.

All signs are that Obama hopes the strategy will give him more leverage with Netanyahu, weakened by January's election in which centrists made surprising gains against his right-wing bloc, to pursue a peaceful resolution with Iran and eventually address the Israeli-Palestinian stalemate.

Obama acknowledged he and Netanyahu have had differences but insisted they shared a "terrific, business-like relationship," often referring to the Israeli leader as Bibi, his popular childhood nickname.