Hamas’ political leader was killed by a predawn airstrike in Tehran on Wednesday, according to Iranian officials who immediately blamed Israel for the apparent assassination. There has so far been no official comment from Jerusalem, but the incident is virtually certain to escalate a Middle East conflict that’s already on the verge of engulfing the entire region.

Iran’s supreme leader, Ayatollah Ali Khamenei, vowed revenge on Israel. He took to social media in the hours after the attack to say that Iran has a “duty” to retaliate. The Qatar-based Mr. Haniyeh, who had been Hamas’ point man in cease-fire negotiations with Israel aimed at ending the war in the Gaza Strip, was in Tehran to attend the inauguration of the country’s new president, Masoud Pezeshkian.

The future of those cease-fire talks is now in doubt. Mohammed bin Abdulrahman bin Jassim Al Thani, the prime minister of Qatar, whose country has hosted numerous rounds of negotiations, condemned the attack in Tehran.

“How can mediation succeed when one party assassinates the negotiator on the other side?” he said in a post on X, summing up the reaction across much of the Arab world.

For Israel, its war against Iran-backed proxies is escalating quickly on multiple fronts. On Tuesday in Lebanon, Israel said it targeted and killed Hezbollah official Fouad Shukur, whom Israel said was responsible for last weekend’s Golan Heights attack that killed 12 Israeli teenagers.

On July 20, Israel struck Yemeni ports controlled by Iran-backed Houthi rebels, a move that came after an apparent Houthi drone attack on Tel Aviv that killed one Israeli. All of those developments come just a few months after Israel and Iran found themselves on the precipice of a direct, all-out war. The two nations seem to be headed in that direction once again.

Secretary of State Antony Blinken told Channel News Asia in an interview Wednesday that the U.S. was not aware of or involved in the incident. He pushed for a cease-fire in Gaza and framed it as the only way to cool tensions.

“One of the things that we’ve been focused on is trying to make sure that the conflict that emerged in Gaza doesn’t spread, doesn’t go to other places, doesn’t escalate, and we’re going to continue to do that as well,” Mr. Blinken said. The secretary of state, who is on a lengthy trip to Asia this week, was working the phones Wednesday, speaking with his counterparts in Jordan and Qatar, among other countries, about the fallout from the attack.

Defense Secretary Lloyd Austin spoke to Israeli Defense Minister Yoav Gallant by phone early Wednesday, the Pentagon said, though the official readout of their conversation did not mention the apparent assassination of Mr. Haniyeh.

The tentacles of Hamas have reached American shores, according to a report by a former federal counterterrorism expert, who said that the Palestinian militant group operates an extensive network of supporters in the U.S. linked to the international Muslim Brotherhood jihadist group.

National Security Correspondent Bill Gertz has all the details on the study from John D. Guandolo, a former FBI agent and former Pentagon counterterrorism strategist who has studied the global Islamist movement extensively. He argues that one key feature of the Hamas-Muslim Brotherhood activities is a close alliance with Marxist and communist groups in the U.S. The report contends that recent pro-Palestinian and anti-Israeli demonstrations in cities and on college campuses across the country should serve as a warning.

The report comes amid other signs that Iran and its proxy groups, including Hamas, are cultivating a deeper foothold in the U.S. Earlier this month, Director of National Intelligence Avril Haines said that Iranian intelligence officials are helping to pay for anti-Israel protests that have erupted in the U.S. and are posing as activists to stoke discord during a U.S. election year. Iran, she said, is increasingly aggressive in trying to influence the U.S. and other countries to undermine confidence in democratic institutions.

Is deterrence still an option in the Middle East? David Daoud, a senior fellow at the Foundation for Defense of Democracies, writes in a new op-ed for The Washington Times that the U.S. can and must step up to the plate for its key ally, Israel.

He writes that America should “demonstrably back Israel’s right to defend itself, including through a campaign in Lebanon, while holding Beirut’s — and not Jerusalem’s — feet to the fire.”

“Washington’s message to Hezbollah should be that, if its provocations continue, it stands to suffer irreversible and inescapable consequences,” he said. “This restoration of U.S.-backed Israeli deterrence could keep the group in check indefinitely.”

Mr. Daoud also spoke to the Threat Status Podcast recently about the seeming inevitability of a full-blown Israel-Hezbollah war.

Facing its most dire security threat since the end of World War II, the U.S. is burdened by inadequate resources, a failing defense industrial base and a national strategy that hasn’t prepared it to take on the combined challenge of near-peer adversaries like China and Russia and aggressive rogue states such as Iran and North Korea.

That was the takeaway from a report by the Commission on the National Defense Strategy, a blue-ribbon bipartisan panel of defense experts. The panel, which briefed lawmakers on its report this week, concluded that the U.S. simply isn’t keeping pace with the threats of the 21st century.

Military Correspondent Mike Glenn has all the details, including this ominous warning from the panel about U.S. preparedness for a major war: “The nation was last prepared for such a fight during the Cold War, which ended 35 years ago. It is not prepared today.”

Venezuela’s military chief is backing embattled President Nicolás Maduro amid escalating protests and a deepening political crisis in the South American country. Mr. Maduro claims to have won reelection over his opponent, former diplomat Edmundo González, in last Sunday’s elections.

But the U.S., European Union, numerous Central and South American governments, and independent observers have cast heavy doubt on the integrity of the election. The Atlanta-based Carter Center said that a technical mission it sent to Venezuela was unable to verify the results of the country’s presidential election and blamed officials for a “complete lack of transparency” in declaring victory for the incumbent. The Atlanta-based group in a statement said that the election “did not meet international standards of electoral integrity and cannot be considered democratic.”

The government’s vote tallies, showing Mr. Maduro as the winner, differ wildly from independent exit polling that shows Mr. González with a significant edge. There have already been reports of several fatalities among protesters who have taken to the streets of cities across the country to challenge the result.

• Aug. 7 — Navigating Global Challenges: A Conversation with Vice Commandant of the Coast Guard Admiral Lunday, Brookings Institution 

• Aug. 8 — Over the Brink: Escalation Management in a Protracted U.S.-PRC Conflict, Center for a New American Security