Iran has launched its widest crackdown in years, saying it arrested more than 700 people in a 12-day sweep on accusations of spying for Israel and seized about 10,000 small drones in Tehran. State media aired what it described as confessions by several of the detainees after weeks of cross-border strikes that ended in a fragile cease-fire earlier this month. In a separate statement, the Islamic Revolutionary Guard Corps’ Quds Base said its forces killed two suspects and detained roughly 50 others—part of a total of 52 people—during raids in the southeastern province of Sistan-Baluchestan. The Guard added that five alleged agents, mostly foreign nationals, were planning drone-borne sabotage operations for Israel’s Mossad intelligence service. Israel’s domestic security agency responded with disclosures of its own. The Shin Bet and national police said they arrested Bashar Hassan Qassem Musa, a 22-year-old Arab Israeli studying information systems at Ben-Gurion University, on suspicion of plotting an attack on a public figure, scattering nails on a main highway and spreading incitement under Iranian direction. Authorities allege he had communicated with an Iranian operative via encrypted channels. Days later, the Shin Bet announced the detention of three additional Israelis accused of photographing and transmitting coordinates of air-defense installations and other sensitive locations to Iranian handlers in exchange for hundreds of thousands of shekels. The parallel waves of arrests highlight an intensifying espionage contest between the two regional rivals even after open hostilities subsided.