Tehran’s proxies unleash violence on several fronts in the Mideast as it senses weakness in adversaries.

The Taliban’s seizure of power in Afghanistan, while swift and dramatic, is neither the first nor the sole challenge to the U.S. and its allies taking place in and around the region. Iran is mounting another, no less significant push. Behind both offensives is the perception that the regional order is failing and the U.S. is retreating.

The factor underlying the Mideast violence earlier this summer seems clear: Iran is trying to assert power across several fronts. It is wielding a variety of assets, proxies and franchises against the full range of enemies it perceives in the region.

Part of the escalation was last month’s fatal drone attack on the merchant vessel Mercer Street in the Gulf of Oman. The Liberian-flagged oil tanker belongs to Zodiac Maritime, a London-based firm owned by Israeli shipping magnate Eyal Ofer. Two people were killed: a British crewman and the Romanian captain.

Responsibility for the attack “clearly points to Iran,” according to a Group of Seven statement Aug. 6. Foreign Ministry spokesman Saeed Khatibzadeh called the accusation “baseless.”

Lebanese Hezbollah’s launch of 20 Katyusha missiles at Israel on Aug. 6 represents a sharp breach of the de facto rules that have largely held along the border since the end of the Second Lebanon War 15 years ago.

The launch itself and the claim of responsibility by Hezbollah—Iran’s proxy—reflect an apparent willingness on the part of the Lebanese Islamic Revolutionary Guard Corps franchise to provoke Israel.

Iran’s IRGC-trained death squads have been busy in remote areas seldom covered by Western media.

On July 14, Iranian dissident, activist and environmentalist Behrouz Rahimi was killed in Suleimania, an Iraqi city near the border with Iran.

Closed-circuit television footage shows a BMW with tinted windows and no license plate tailing Mr. Rahimi. Gunmen then opened fire from the car. Mr. Rahimi died from his wounds in the hospital. His wife later cited recent threats against her husband from Iran’s Intelligence Ministry.

Iran hasn’t made a statement on the killing.

This month, Musa Babakhani, a leader of an Iranian Kurdish opposition party, went missing and days later was found dead in the Guli Suleimani Hotel in Erbil, in northern Iraq. His body showed signs of torture. Mr. Babakhani’s Kurdistan Democratic Party of Iran accused the Islamic Republic of the murder. No one has been arrested for either killing.

Further south in Iraq, IRGC-supported Shiite militias are continuing to attack U.S. facilities. There are 2,500 U.S. service personnel in the country, stationed at Iraqi military positions such as the Al Asad air base. Twenty strikes have happened since April, including eight on U.S. facilities using Iranian-made drones.

On the Syrian front, an offensive is under way in Daraa province, intended to strengthen the Iranian presence in the country.

The offensive on the town of Daraa Al-Balad is being spearheaded by the Iran-allied Fourth Division of the Syrian Arab Army. It is directed against the remnants of the Syrian rebels in the area, who now work in cooperation with Russia. Iran maintains influence there through the Fourth Division, the Air Force Intelligence Branch and also the presence of IRGC and Lebanese Hezbollah personnel.

This is strategic real estate, facing the border with Israel and the Golan Heights as well as the border with Jordan. The former rebels are fighting back, and the situation in Daraa is more strained than at any time since the Syrian regime returned to the area in mid-2018, according to an Aug. 5 statement by the United Nations High Commissioner for Human Rights.

We have a drone attack, Katyusha bombardment, killings of dissidents, strikes on U.S. forces in Iraq, and an offensive to consolidate control near the Syria-Israel-Jordan border. Why is all this happening now?

First, hard-line Iranian President Ebrahim Raisi, who took office Aug. 5, appears eager to demonstrate his sway. More broadly, Iran sees this an auspicious moment thanks to a confluence of events.

The new government in Israel lacks strategic heft and experience and is dealing with a fourth wave of Covid. The Iranians seem keen to put Prime Minister Naftali Bennett to the test.

Iran sees the U.S. administration completing a headlong flight from Afghanistan. This will reinforce the sense of a crumbling regional order.

Washington also may be looking to end commitments in Iraq and Syria, in line with bringing down the curtain on the so-called forever wars. On July 26 President Biden committed to removing all U.S. combat troops from Iraq by year-end.

U.S.-allied Kurdish leaders in Syria, Mazloum Abdi and Ilham Ahmed, made subsequent statements hinting at an imminent American withdrawal from Syria.

Tehran senses it is time to push forward, against weakened and isolated enemies hesitant to push back.

Jonathan Spyer is director of the Middle East Center for Reporting and Analysis and a research fellow at the Middle East Forum. He is author of “Days of the Fall: A Reporter’s Journey in the Syria and Iraq Wars.”

(Middle East Forum / Wall Street Journal).