With every day that passes in the advance by Yemeni loyalist forces into the strategically vital port of Hodeidah, the more we are learning about the depth of Iran's support for the Houthi rebels in the country's long-running civil war.
From the outset of hostilities, the Iranians have repeatedly denied sending arms to the Houthi rebels. They have also rigorously rejected any suggestion that they have been in any way responsible for the failure of diplomatic efforts to resolve the conflict, even though it has been invariably the Houthis who have stymied the peace process.
But with Yemeni loyalist forces, with the backing of the United Arab Emirates, now claiming to have seized control of Hodeidah airport, a vital milestone in their effort to reclaim control of the entire city, damning evidence is starting to emerge that points to the true extent of Iran's involvement in the conflict.
The capture of the airport, which comes following a week of fierce fighting and has claimed the lives of four Emirati soldiers, puts loyalist forces and their Emirati backers in a strong position, as it should allow them to begin their advance along the coast towards the port area, the primary objective of the offensive.
The port is a vital access point for humanitarian aid supplies being shipped into the country, such as food and medicine. Aid agencies estimate around 70 per cent of supplies to Yemen pass through Hodeidah, which is controlled by the Houthis, who have been accused of disrupting vital aid supplies by indulging in corruption and extortion. As a result 22 million Yemenis are short of food, with more than 8 million facing the direct threat of starvation.
The loyalists' offensive has been launched to break the Houthis' stranglehold over the port, thereby freeing up the flow of vital aid supplies to the wider Yemeni population. But while the loyalists, by capturing the airport, have achieved a vital breakthrough, coalition commanders are well aware many difficult challenges lie ahead, not least because of the tactics being employed by the Houthis and their Iranian backers.
The Houthis have imposed a reign of terror over Yemen’s civilian population since seizing control of Hodeidah in 2014, a fact that has been made evident following reports that the Houthis have been staging summary executions of Yemeni teenagers who refused to fight for their cause. The Houthis have also been accused of using human shields to defend their positions against the loyalists’ advance, and have also deployed thousands of mines and improvised explosive devices.
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Coalition commanders, who say they are now in full control of the airport, estimate they have cleared around 30,000 mines and booby-trap devices the Houthis had placed at key locations around the airport. The concern now, though, is that the Houthis will use similar tactics to defend Hodeidah itself. There are believed to be around 5,000 die-hard fighters based in the city centre, which has already been mined extensively, thereby making the coalition’s task of liberating the city even more challenging.
This has prompted the Yemen Coalition for Monitoring Human Rights Violations to issue a strongly-worded statement criticising the attitude of some humanitarian groups to the conflict, where they have often blamed the Saudi-led coalition, rather than the Houthis, for causing Yemen’s humanitarian disaster. “We have been documenting and reporting violations committed by all parties of the conflict, including the Arab coalition,” the statement reads. “It seems necessary to remind the international community, including humanitarian representatives of the UN, of the violations committed by the Houthis, of which they appear to be ignorant.”
Apart from the Houthis’ wilful disregard for the well-being of Yemeni civilians, the other alarming development to emerge from the first stages of the loyalist offensive to recapture Hodeidah is the extent of the military support the Houthis have received from Iran.
This was laid bare earlier this week when coalition officials presented reporters in Abu Dhabi with a display of the Iranian-made weapons they have found during the offensive to clear the airport. These included drones, a heavy-calibre sniper rifle, roadside bombs that had been cleverly disguised as rocks and even a "drone boat" that had been filled with explosives but had failed to detonate. Officials showed components bearing Iranian inscriptions, including equipment that had been used to produce and load fuel for the sophisticated rockets the rebels have fired across the border at Saudi Arabia. The Saudis say around 150 ballistic missiles have so far been fired at Saudi territory.
Some of the weapons on display have recently featured in the report produced by Conflict Armament Research, an independent group that gained access to materiel through the UAE’s elite Presidential Guard. These included roadside bombs disguised as rocks, which bear a striking resemblance to similar weapons used by Hezbollah in southern Lebanon.
The production of clear proof that Iran has been arming the Houthi rebels prompted the usual response from Tehran. Iran’s mission to the UN said it had no comment to make on the specific allegations “other than reiterating that Iran has not sent and does not send armaments to Yemen".
These denials, though, have an increasingly hollow ring to them in the face of the mounting evidence that points to Iran’s involvement in the conflict, and also helps to explain how a ragtag tribal militia like the Houthis managed to seize large tracts of the country in the first place.
The outside world has, for too long, turned a blind eye to Iran's involvement in the Yemen conflict. The time has now come for international institutions like the UN to hold the Iranians to account for their actions.
Con Coughlin is The Daily Telegraph’s defence and foreign affairs editor.