As Mr. Modi came down from an Indian Air Force aircraft at the Allama Iqbal Airport, lining up on either side of the red carpet were men of the Pakistan Air Force. With traditional Heckler & Koch G3 rifle mounted with a six-inch bayonet, the personnel stood on either side, hardly a couple of feet away from the two Prime Ministers.

A former Protocol Officer told The Hindu that nothing about the Lahore visit fitted into any rule book. It was a completely impromptu visit, he said. “We don’t have a protocol for drop-ins.”

Another officer who handled protocol during Atal Bihari Vajpayee’s Lahore visit in 1999 recalled that “we preferred Bhangra to the ceremonial welcome by the armed forces”. “As Indians, we remember the incident involving a Sri Lankan soldier at a guard of honour for Prime Minister Rajiv Gandhi on July 30, 1987.”

On July 30, 1987, a day after the India-Sri Lanka peace accord was signed in Colombo, the then Indian Prime Minister, Rajiv Gandhi, was hit with the butt of a rifle by Vijitha Rohana Wijemuni, a Sri Lankan Navy sailor, as Mr. Gandhi was inspecting a guard of honour. Recalling that moment, security experts, too, sounded a note of caution.

“It is very strange. When I saw him [Mr. Modi] walk past the Pakistan Air Force personnel along with Nawaz Sharif on the red carpet, what struck me was the Rajiv Gandhi moment,” Maj.Gen. (retd.) Ashok K. Mehta, who served in the Indian Peace Keeping Force in Sri Lanka, told The Hindu. “The spontaneity of the visit clouded everything else,” he said.