MUNICH — Israeli Prime Minister Benjamin Netanyahu on Sunday issued a stark warning to Iran, saying his nation was prepared to go to war if the Iranians continue to test Israeli red lines in Syria.

Brandishing what he said was a fragment of an Iranian drone shot down over Israeli territory Feb. 10, Netanyahu cited Iran’s efforts to “colonize” Syria with a permanent military base and use the war-ravaged nation as a launchpad for operations in Israel.

“Israel will not allow Iran’s regime to put the noose of terror around our neck,” he said. “We will act without hesitation to defend ourselves. And we will act, if necessary, not only against Iranian proxies that are attacking us but against Iran itself.”

The warning came in a widely anticipated speech Netanyahu delivered to the Munich Security Conference, the world’s most prominent gathering of its type. The saber-rattling address was followed later Sunday by a speech from Iranian Foreign Minister Mohammad Javad Zarif. 

“Mr. Zarif, do you recognize it?” Netanyahu asked as he held the drone fragment aloft. “You should. It’s yours. You can take back with you a message to the tyrants of Tehran: Do not test Israel’s resolve.”

In his own speech, Zarif dismissed the Israeli leader’s address as a “cartoonish circus.”

The Iranian foreign minister cited “almost-daily incursions into Syrian airspace” by Israeli aircraft, Israel’s strikes against targets in Lebanon and its occupation of Palestinian lands. 

“Israel uses aggression as a policy against its neighbors,” he said. He suggested that Netanyahu was deliberately raising tensions as a way to distract from his troubles at home. 

Netanyahu has for years been making dire predictions about the potential for war with Iran, a regional power that he on Saturday described as “the greatest threat to our world.” 

But the dynamic is different now: The Israeli leader is weakened domestically, with police investigators recommending that he be charged with corruption. He also feels emboldened abroad, as he finds new allies in President Trump’s United States and in an Arab world that has been increasingly willing to put aside its longtime enmity toward Israel to oppose mutual rival Iran.

The latest escalation of Middle East tensions began last weekend when Israel shot down an Iranian drone that had crossed into its airspace. Israel carried out airstrikes in Syria in retaliation for the incursion, but one of its F-16 fighter jets crashed while under fire.

The dueling speeches by Netanyahu and Zarif came with the fate of a landmark 2015 nuclear accord between Iran and the world’s biggest powers hanging in the balance.

Citing Munich’s history as the setting for an infamous deal with Nazi Germany on the eve of World War II, Netanyahu used his Sunday speech to bash the 2015 agreement, saying it had “unleashed a dangerous Iranian tiger in our region and beyond.” 

The future of the deal, which was negotiated during the Obama administration, has been cast into doubt by Trump, who has said it must either be revamped or scrapped. Under the agreement, Iran agreed to end the nuclear activities that the world powers considered most troubling in exchange for an end to crippling sanctions.

Netanyahu called on European allies to take a tougher line against Iran, following the United States’ lead.

“Appeasement never works,” he said. “The war to prevent war is getting late — but it’s not too late.”

Illustrating the unofficial alliance between Israel and Arab powers against Tehran, Saudi Foreign Minister Adel al-Jubeir reinforced Netanyahu’s points. He called for the nuclear deal to be revised with enhanced inspections and tougher penalties over what he called continued Iranian support for terrorism.

“The world has to extract a price from Iran for its aggressive behavior,” he said.

Netanyahu predicted that if the deal cannot be revised in a way that satisfies Trump and the United States walks out on it, Iran will do “nothing.” 

Zarif called that idea “delusional.”

“If Iran’s interests are not secured, Iran will respond. We’ll respond seriously,” he said. “People will be sorry.”

Zarif also called on rival nations to join Iran in a Persian Gulf dialogue to cool tensions at a time when the region was “dangerously close to escalating conflicts.”

Former U.S. secretary of state John F. Kerry, who was instrumental in negotiating the nuclear accord, rejected Netanyahu’s criticism, calling the Israeli leader’s claim that the deal would enable Iran to develop an arsenal of nuclear weapons “just not accurate.” 

“If your house is on fire, are you going to refuse to put it out because you’re concerned that it might light on fire again in 15 years?” he asked, a reference to Netanyahu’s claim that Iran would develop warheads over the coming decade or two. “Or are you going to put it out and use the intervening time to do the best you can to prevent it from ever catching fire again?”

Making clear that nervousness about the future of the Iran deal extends broadly across the nations that helped negotiate it, a senior Russian lawmaker said he agreed with Kerry despite the many other issues that divide the Kremlin and the United States.

“The choice in Iran is between the agreement, the deal and a war,” said Alexei Pushkov, a member of the upper house of Russia’s parliament. “Okay, you bomb Iran, and then you do what? What happens next?”