Italian special forces have deployed "drone-killing" weapons to protect world leaders attending Pope Francis's funeral on Saturday.
Soldiers in combat uniform have been mobilised to St Peter's Square to guard against aerial terrorist attacks.
The open-air funeral will take place in front of St Peter's Basilica, with dignitaries seated outside.
The threat posed by drones has alarmed counter-terror agencies over the past decade, with concerns heightened following the Russian invasion of Ukraine, where expertise in unmanned aerial vehicles has advanced significantly.
Soldiers in combat uniform have been mobilised to St Peter's Square to guard against aerial terrorist attacks
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Pallbearers carry the coffin of the late Pope Francis to St. Peter's Basilica
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A no-fly zone is already in place around the Vatican area.
The Telegraph observed soldiers carrying two different versions of anti-drone weapons, which block signals between controllers and drones, forcing them to crash.
"It is a frequency jammer," explained one soldier. "If we find a drone we can jam the signal to the controller and force it to the ground."
A second anti-drone weapon deployed by the Italian air force featured three barrels, each about four inches wide, with what appeared to be a large battery pack.
In total, 170 national delegations are expected to attend the funeral, including Donald Trump, Sir Keir Starmer and Volodymyr Zelensky.
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Members of the Italian armed forces are seen with an anti-drone gun at the Vatican in Rome
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The Prince of Wales will also be present among the dignitaries.
Authorities anticipate between 400,000 and a million mourners to flood into Rome.
Nello Musumeci, the minister for civil protection and maritime policies, told reporters he expected "over a million" pilgrims.
The warm, sunny weather forecast for Saturday is likely to encourage larger crowds.
Giant screens will be erected along via della Conciliazione so that crowds can watch proceedings.
The security operation involves coordination between the Vatican's Swiss Guard and Italian forces.
Despite their ceremonial appearance, Swiss Guards undergo rigorous military training and must be Swiss, aged 19 or over and single.
The Vatican also maintains its own security police force called the Corps of Gendarmerie.
Pope Francis died at the age of 88, the Vatican confirmed on Monday
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Multiple Italian security forces are involved, including the Carabinieri and the Guardia di Finanza
Reuters
Multiple Italian security forces are involved, including the Carabinieri and the Guardia di Finanza.
The logistical challenge is complicated by staging the funeral outdoors on Vatican territory, which falls under Swiss Guard protection.
Police reinforcements are being drafted from other regions of Italy to bolster security.
Snipers will be positioned on rooftops around the Vatican and authorities will conduct rigorous checks of drains and underground spaces.
Some roads around the Vatican are already closed.
Police boats have been deployed on the River Tiber, while officers conduct checks at train and metro stations.
The security presence is highly visible, with 400 local traffic police and an estimated 2,000 security agents deployed.
Around 7,000 volunteers are helping mourners, distributing water and providing assistance.
