Four hundred Israelis looked at their cellphones Wednesday night and discovered just how closely their government is keeping tabs on them during the coronavirus crisis.

The country’s Health Ministry had sent tailored text alerts telling citizens that a digital review of their movements showed they had been in proximity to a person known to have tested positive for the virus.

It was not just an advisory. The text also delivered an instant quarantine order, in keeping with ever-tightening restrictions dictated by the Israeli government. “You must immediately go into isolation [for 14 days] to protect your relatives and the public,” the notice said.

Israelis who have tested positive also received messages informing them that their cellphone data would now be used to warn others who may have been exposed to them, according to a statement from the Health Ministry.