The leader of the Afghan Taliban who was killed in a U.S. airstrike over the weekend reportedly visited Iran just hours before his death.

Mullah Akhtar Mansour, an Afghan citizen, was carrying a Pakistani passport when he entered the country Saturday at the Taftan transit point in western Pakistan, a popular crossing for cargo trucks, VOA news reports.

The passport reportedly had the name Wali Muhammad on it, but also had Mansour’s photo.

It wasn’t immediately clear why Mansour was in Iran, but five hours after he crossed the border, he was killed in the drone strike while traveling to Quetta, officials said.

A passport control photo also showed Mansour entering Pakistan, and he previously crossed into Iran at the same location on April 24, VOA News reported.

Western diplomats in Kabul have said Mansour had been in contact with Iran and Russia in recent months, in a bid to diversify his support base away from Pakistan. Pakistan's ISI secret service has long been suspected of supporting the Taliban leadership in cities across the border from Afghanistan, notably Quetta and Peshawar.

Russia and Iran also are believed to have reached out to Taliban groups in recent months as a counterweight to the Islamic State terror group's presence in Afghanistan.

A senior Afghan Taliban figure said Tuesday that Mansour’s death could make the insurgent movement stronger by bringing back dissident commanders and unifying the movement's ranks.

Mullah Mohammad Ghous, a foreign minister during the Taliban's 1996-2001 rule of Afghanistan, told The Associated Press Mansour's death cleared the way for those who left after he became leader to return to the insurgency.

His death has been confirmed by some senior Taliban members, as well as Washington and Kabul. The Taliban has yet to formally announce his death.

Mansour had led the Taliban since last summer, when the death of founder Mullah Mohammad Omar became public. Mansour ran the movement in Mullah Omar's name for more than two years. The revelation of Mullah Omar's death and Mansour's deception led to widespread mistrust, with some senior leaders leaving to set up their own factions.

Some of these rivals fought Mansour's men for land, mostly in the opium poppy-growing southern Taliban heartland.

Ghous said a faction loyal to the leader of a major breakaway faction, Mullah Mohammad Rasool — who is believed to be detained in Pakistan — could rejoin the main branch "bringing greater strength."

"Once the death of Mullah Akhtar Mansour is confirmed, Mullah Rasool's group will have no excuse," he said.

Mansour is widely said to have been a major player in Afghanistan's multi-billion-dollar drug production and smuggling business, which along with other contraband helps fund the insurgency.

"The Taliban needs financial and strategic support, so as leader of the movement Mullah Akhtar Mansour had to look for it in difference places — and that meant he had to travel to different countries," Ghous said, adding that Mansour regularly visited Dubai, Qatar and other countries including Iran, which borders western Afghanistan.

Ghous said that it was widely accepted within the upper ranks of the Taliban that Iran also facilitated contact with Russia for Mansour. "We all know Iran and Russia are linked nowadays, so if Mullah Akhtar Mansour is meeting with Iran it must be with the knowledge of Russia."

Another respected veteran in the insurgency, religious scholar Mullah Hameedullah, agreed that Mansour's death removed an obstacle to unity.

As senior figures gather in Pakistan to discuss the movement's future and who should be leader, both Ghous and Hameedullah said the choice of successor would impact whether or not the Taliban chooses war or peace.

The Associated Press contributed to this report.