"The increased pace of transfers in recent months, which officials said include missiles and small arms, could exacerbate a security headache for the United States ...
"Much of the recent smuggling activity has been through Oman, which neighbours Yemen, including via overland routes that take advantage of porous borders between the two countries, the officials said."
Over the last 10 days or so we have seen an increase in media reports highlighting the "Iranian threat" in Yemen, and the latest story from Reuters fits that pattern.
While it's true that the Houthis have Iranian backing, the extent of Iran's tangible support is unclear and media coverage is often alarmist and based on very slender evidence. During the last week or so, for example, there have been claims – still unconfirmed – that rockets fired from Yemeni territory at American warships in the Red Sea (harmlessly, as it turned out) had been supplied by Iran along with the radar systems that guided them. Meanwhile, an Iranian naval "flotilla" (consisting of a single 48-year-old frigate and its supply ship) is supposedly heading for the area to challenge the might of the US Navy.
The effect of this coverage has been to divert attention from the most horrific event of the Yemen war so far: Saudi Arabia's bombing of a funeral on October 8 which is reported to have killed at least 140 people and injured more than 500.
The Saudis, who are fighting the Houthis, initially denied the bombing. They now admit that they did it and it shouldn't have happened but claim it had not been officially authorised. Needless to say, this deeply embarrassed the US and Britain which are the kingdom's chief arms suppliers, prompting them to call for a ceasefire.
The most notable feature of the Reuters story is that it goes beyond other recent reports by alleging that Oman is complicit in supplying Iranian weapons to the Houthis. The timing of this allegation is especially significant because it could undermine Oman's role as a mediator in the Yemeni conflict at a crucial moment – just as the 72-hour ceasefire is getting under way.
When the bombing of Yemen began in March last year, Oman was the only one among the six GCC states that did not join the Saudi-led coalition. This was seen at the time as a signal that it was available to help with mediation, and it has since been doing so.
Oman has also been involved in securing the release of foreigners kidnapped by the Houthis and, following the funeral massacre, sent a plane to Sanaa – with the Saudis' agreement – to evacuate some of the wounded.
The suggestion in the Reuters story is that Oman has not been as diligent as it might have been in preventing "anti-ship missiles, explosives, money and personnel" from crossing into Yemen. There's a long history of commercial smuggling on the Omani-Yemeni border which predates the war, but its use as a possible supply route for the Houthis' weaponry does raise some questions.
The distance from the Omani border to the nearest Houthi-controlled territory is about 500 miles as the crow flies, and considerably more overland (see map). This vast area between the border and the Houthis is sparsely populated but controlled, at least in theory, by the Saudi-backed anti-Houthi forces and, in a few places, by al-Qaeda who are no friends of the Houthis either.
If Iranian weapons are indeed getting through to the Houthis by this route it would seem that the Saudi-led coalition and local security forces are missing a lot of opportunities to intercept them.