US President Donald Trump, who launched strikes on Iran together with Israel on Saturday, initially projected the war to last four to five weeks, but has since sought to justify a broad, open-ended war.
In the meantime, Iran has launched missile and drone strikes against not only Israel and US forces but also a host of countries across the region allied to the US, paralysing globally vital energy shipments from the Gulf along with hundreds of busy short- and long-haul flight routes.
Netanyahu rejected the idea of the conflict lasting years, like previous wars in the region.
"I said it could be quick and decisive. It may take some time, but it's not going to take years. It's not an endless war," Netanyahu told Fox News on Monday.
Israeli Lieutenant Colonel Nadav Shoshani told an online briefing the duration of the military campaign could change, depending on developments, adding: "We have prepared a general scope of weeks."
Asked if Israel could deploy ground forces to Iran, Shoshani said that was unlikely.
Explosions shook buildings across Tel Aviv as air defences intercepted incoming Iranian missiles.
Israel attacked the Tehran complex of Iran's state broadcaster IRIB in Tehran and Hezbollah militants in towns across Lebanon.
The Israeli military said it had sent more troops into southern Lebanon and positioned them at points near the border as part of "forward defence".
After its November 2024 ceasefire with Hezbollah, a Shi'ite militia that serves as an Iranian proxy force, Israel kept ground troops in Lebanon at five vantage points.
Early on Tuesday, two drones, apparently from Iran, struck the US embassy in Riyadh, causing minor damage and starting a fire, and at least eight more drones were intercepted before reaching the city, Saudi Arabia's Defence Ministry said.
Hundreds of civilians have been killed in Iran, Israel, Lebanon and other nations since the US and Israel launched the war by killing Iranian Supreme Leader Ali Khamenei from the air on Saturday.
Iran's Islamic Revolutionary Guard Corps, which reports to the Supreme Leader, said its navy had destroyed the main command building and headquarters of a US air base in Bahrain in what it described as "Operation Promise of the Truth 4".
The US State Department and the White House did not immediately respond to requests for comment.
US Secretary of State Marco Rubio warned "the hardest hits are yet to come from the US military".
Asked how long he expected the United States to be engaged in Iran, Rubio said: "We believe the objectives we have set for this mission, the destruction of (Iran's) ballistic missile capabilities, both launch capabilities and manufacturing, can be achieved without ground forces ...
"Right now we are not postured for ground forces. But obviously the president has those options and he is not going to rule out anything."
A member of Iran's Assembly of Experts, charged with choosing a new Supreme Leader, said picking Khamenei's successor "won't take long", Iran's ISNA news agency reported.
The US military said it had struck more than 1250 targets in Iran so far and destroyed 11 Iranian ships. Six US service personnel have been killed, all in Iran's retaliatory attacks over the weekend on Kuwait.
The conflict has thrown global air transport into chaos and shut down shipping through the Strait of Hormuz, where one-fifth of the world's oil trade skirts the Iranian coast, sending oil prices surging.
Major Gulf hubs, including the world's busiest international airport Dubai, which usually handles over 1000 flights a day, remained closed for a fourth day. That has left tens of thousands of passengers stranded.
Asian airline shares extended losses, with carriers closely monitoring fuel price spikes and bookings surging as passengers switch from Middle Eastern airlines.
Global oil and gas shipping rates soared, with supertanker costs in the Middle East hitting all-time highs, after Tehran targeted ships passing through the Strait of Hormuz, according to shipping data and industry sources.
Trump has said the US faced an imminent threat from Iran that justified the war, although he gave no specifics and some US lawmakers said he had shown no evidence.
Rubio told reporters the US had acted pre-emptively because it knew of its close ally Israel's plan to strike Iran and knew Tehran would respond, putting US bases at risk.
Trump on Monday said he had ordered the attack to thwart Tehran's nuclear program and a ballistic missile program that he said was growing rapidly.
Trump's assault on Iran is the biggest US foreign policy gamble in decades and a major political risk for his Republican Party in this year's midterm elections. Only one in four Americans supported the Iran attack in a weekend Reuters/Ipsos poll.
