The kindling that ignited the most recent escalation between Israel and Iran on Sunday was in Lebanon, which has been battered repeatedly in the conflict between the other two countries as they have sought to impose their own rules in the Middle East.
On Sunday, Hezbollah, the Lebanese armed group that is backed by Iran, attacked Israel. That triggered Israeli retaliation in Beirut’s southern suburbs, a bastion of support for the group. Iran then followed through on its threat to attack northern Israel in response to strikes in the Beirut area.
Analysts say the calculations of leaders in both Israel and Iran led them to draw a hard red line through Beirut, the Lebanese capital, precipitating the escalation and threatening to return the countries to full-blown war.
“Lebanon is caught between Iranian and Israeli interests and a site where neither is willing to compromise,” setting the stage for the escalation, said Lina Khatib, an associate fellow at the Chatham House research institute in London.
With President Trump trying to end the U.S.-Israeli war against Iran, Tehran’s leadership insists that any peace must apply to Lebanon, as well. But Prime Minister Benjamin Netanyahu of Israel has rejected that linkage in favor of continuing the Israeli invasion against Hezbollah.
Mr. Netanyahu said Iran and Hezbollah had tried to “impose a new equation” by firing at Israel in response to its attacks on Hezbollah in Beirut. He said that equation was “unbearable and unacceptable to me.”
Israeli leaders now see Iran as trying to carve out a “zone of immunity” for Hezbollah to operate in Lebanon without fear of attack, which would erode Israel’s regional position, said Aaron David Miller, a former State Department official and Middle East expert.
After the U.S. and Israel attacked Iran in late February, Hezbollah joined the fight with a rocket barrage on Israel. The Israeli military responded with a massive military assault that has killed more than 3,000 people and displaced more than one million, according to Lebanese officials.
Lebanon has long been buffeted by competing powers, having been a battleground for Israel and Palestinian militants, among others. Lebanon’s government has been negotiating with Israel in hopes of ending the war, but it is not a party to the conflict.
The Lebanese government also neither holds nor exercises any control over Hezbollah, which is funded and overseen by Tehran, and remains Lebanon’s most powerful military and political force.
Some Lebanese — including Joseph Aoun, the Lebanese president — have criticized Hezbollah for dragging the country into a devastating war with Israel at what they say is Iran’s behest. Mr. Aoun has called for Lebanon’s government to assert more control over the country’s destiny, although that faces substantial obstacles in both Israel and Hezbollah.
Mr. Aoun has also exchanged barbed remarks with Iranian officials in recent days, criticizing Iran for “using Lebanon as a bargaining chip in their negotiation with the United States” in an interview with CNN.
Iran had demanded a halt to the Israeli offensive against Hezbollah as part of the truce with the United States and Israel that went into effect in April. But Israel continued its invasion of Lebanon, vowing to continue occupying parts of southern Lebanon until Hezbollah was disarmed.
Iran’s leadership is now seeking to pressure Israel to scale back its attacks against its ally. They hope that the escalation will lead Mr. Trump to rein in Israel, as the president appears eager to extricate himself from the unpopular and costly war in the Middle East, Mr. Miller said.
“They are clearly risk-ready and emboldened, and interested in creating a new normal,” said Mr. Miller. At the same time, he said, Mr. Trump is increasingly “risk-averse.”
After the escalation ended on Monday, Mohammad Bagher Ghalibaf, the speaker of Iran’s Parliament and the chief negotiator with the United States, said that Iran had “disrupted the equation of a cease-fire on paper and its repeated violations in the field.”
Israel Katz, the Israeli defense minister, insisted on Monday that Israel was still willing to risk another escalation with Iran, if it sees a need to strike Beirut.
