Lebanese and Iraqi politicians denounced Israeli strikes on their territory as a “declaration of war” on Monday as a suspected Israeli aircraft struck another Iran-linked target in Lebanon, marking a new escalation in tensions.

The attack on a Palestinian facility in eastern Lebanon’s Bekaa Valley was the fourth in the space of just a little over a day to hit locations tied to Iranian-backed groups in Lebanon, Syria and Iraq. The strike came just hours after a threat by Lebanon’s Iranian-backed Hezbollah movement to down any Israeli drone that overflew the country and appeared designed to send the message that Israel won’t be deterred.

Israel has acknowledged only the strike in Syria, carried out late Saturday night by warplanes against an Iran-linked military base southeast of Damascus. The Israeli military said the strike thwarted a plot by Iran’s elite Qods Force to attack Israeli territory using multiple exploding drones. There was no independent confirmation that such a plan existed.

The other apparent Israeli attacks targeted a Hezbollah media office in Beirut’s southern suburbs early Sunday morning and the convoy of a militia commander in the western Iraqi province of Anbar in the afternoon. These came amid mounting signs that Israel is stepping up its campaign to curtail Iran’s expanded military activities in the Middle East by hitting the allied militias that often work on Tehran’s behalf. 

Israeli military spokesman Lt. Col. Jonathan Conricus declined to confirm or deny that Israel had carried out any of the strikes in Iraq or Lebanon.

The spike in military activity was in contrast to diplomatic efforts at easing tensions between the United States and Iran in the French resort city of Biarritz, where Iranian Foreign Minister Mohammed Javad Zarif made a surprise appearance Sunday at the summit of the Group of 7 leaders. He was invited by French President Emmanuel Macron as part of a French push to defuse tensions between the United States and Iran over the unraveling of the Iran nuclear agreement.

Macron told reporters Monday that he hoped to arrange a meeting between President Trump and Iranian President Hassan Rouhani within weeks. Rouhani said he was open to a meeting, and Trump said he had “a good feeling” that the encounter would take place.

In the Middle East, however, there were mounting fears that the tensions unleashed by the recent Israeli strikes will escalate further.

Lebanese President Michel Aoun told the U.N. Special Envoy for Lebanon that he regarded the apparent Israeli drone attack on the Hezbollah office in Beirut as a “declaration of war” that violated the U.N.-backed agreements that ended a devastating war between Israel and Hezbollah. He said Lebanon reserved the right to retaliate for the violation of Lebanese sovereignty represented by the attack on the Hezbollah office, although Lebanon’s army lacks the military capability to take on Israel. Under an arrangement that ended the Lebanese civil war, Hezbollah remains the country’s most powerful military force.

Similar language was used by one of the biggest blocs in Iraq’s parliament, the Iran-allied Fateh coalition, which called the strike that killed a commander and at least one other militia member of the Kataeb Hezbollah group a “declaration of war.” The attack followed four blasts over the past month at Iranian-backed militia bases in Iraq that the country’s powerful militias blame on Israel.

In Tehran, Rouhani’s spokesman, Ali Rabiei, warned that Israel would “pay a high price” for its attacks. He indicated however that Iran would not respond directly, citing Hezbollah’s threat to down Israeli drones that was delivered in a speech Sunday by the Hezbollah leader, Hassan Nasrallah.

Nasrallah’s comments “send a clear and severe message to the Zionist regime that its brazen acts of aggression will not go unanswered,” said Rabiei, referring to Israel.

The apparent Israeli attack on a relatively minor Palestinian faction in Lebanon’s Bekaa Valley seemed designed to send the opposite message: that Israel can and will continue to strike at will beyond its borders. 

The base was controlled by the Popular Front for the Liberation of Palestine-General Command, a small, radical faction that is aligned with Iran and Hezbollah. Lebanon’s official National News Agency said the base was hit by three blasts shortly after 1 a.m., causing damage but no casualties. 

The PFLP-GC said in a statement that the blasts were caused by an Israeli drone, but a Lebanese Army official said he believed airstrikes were responsible. Neither the Lebanese army nor Hezbollah have the capacity to shoot down Israeli warplanes flying at high altitude, the official said, speaking on the condition of anonymity because he was not authorized to speak to the press.