Speaking on condition of anonymity, the sources said their assessment was based on a series of developments in and around Islamabad.

They said two US C-17 Globemaster military transport aircraft had landed at Noor Khan Airbase in Rawalpindi, near the capital.

Authorities have also temporarily closed roads leading from the airbase to Islamabad’s high-security Red Zone, indicating heightened security measures.

In addition, major hotels in the capital, including the Serena and Marriott, are being cleared of guests, with no new bookings allowed until Friday, the sources said.

The Serena Hotel previously hosted the first round of US-Iran negotiations on April 11.