Israel launched a powerful airstrike on Evin Prison in northern Tehran on Monday, targeting one of Iran’s most infamous detention centers in what it described as its most forceful assault on the Iranian capital to date. The strike came just a day after the United States formally entered the conflict, marking a dramatic escalation in the ongoing hostilities.

Evin Prison, a symbol of Iran’s authoritarian rule and notorious for housing political prisoners since the 1979 revolution, was left in ruins, according to footage released by Iran’s state broadcaster IRIB. Videos showed rescue workers sifting through debris and carrying wounded individuals, while Iran’s judiciary-run Mizan outlet reported urgent measures were being taken to safeguard the health and safety of inmates.

Israel’s military said it also struck command centers of the Islamic Revolutionary Guard Corps (IRGC) in Tehran, targeting what it called the regime’s “repression infrastructure.” Defence Minister Israel Katz declared that the Israeli Defence Forces were hitting regime targets with “unprecedented force.”

Iran has issued repeated threats of retaliation since U.S. President Donald Trump authorized the use of 30,000-pound bunker-buster bombs on Iranian underground nuclear facilities on Sunday. Yet more than 24 hours later, Iran has not responded directly against the United States. Instead, Tehran has continued missile attacks on Israel, which intercepted at least one missile early Monday.

The Mideast conflict’s impact on global markets remained limited. Despite fears of oil supply disruptions, Brent crude futures dipped slightly, trading at $76.79 a barrel by midday Monday. Analysts suggested that traders remained skeptical about Iran following through on threats to shut down oil flows through the Gulf.

Iranian media offered conflicting reports on the extent of the damage in Tehran, a city of 10 million now partially evacuated after 10 days of Israeli air raids. A strike was reported on a power station near Evin, resulting in localized outages. Iran’s student news agency said Shahid Beheshti University was hit, though the university denied it.

Meanwhile, the question of succession to Iran’s Supreme Leader Ayatollah Ali Khamenei has gained urgency. Sources familiar with the matter said the race to identify a successor has narrowed to two key figures: Khamenei’s son, Mojtaba, and Hassan Khomeini, the reform-minded grandson of the Islamic Republic’s founder. Khomeini has recently gained momentum as a more palatable option both domestically and abroad.

While President Trump has maintained that the U.S. seeks only to dismantle Iran’s nuclear program, his recent comments hinted at broader ambitions. “If the current Iranian Regime is unable to MAKE IRAN GREAT AGAIN, why wouldn’t there be a regime change??? MIGA!!!” he posted on social media, openly contemplating the overthrow of Iran’s government.

Since Israel’s initial surprise strike on June 13 that killed multiple top Iranian commanders, Iranian officials report over 400 deaths, mostly civilians. Israel, for its part, claims Iranian missile strikes have killed 24 people and injured hundreds — the most damage Iranian projectiles have ever inflicted on Israeli soil.

Iran’s capacity to respond has been significantly diminished following Israel’s destruction of Hezbollah in Lebanon and the fall of Syrian President Bashar al-Assad, long a key Iranian ally. Though Iranian lawmakers have floated the possibility of closing the Strait of Hormuz — a vital artery for global oil shipments — U.S. Secretary of State Marco Rubio dismissed the threat as “economic suicide.”

“We retain options to deal with that,” Rubio said, signaling the U.S. would act swiftly against any move to restrict oil flows.