Western intelligence has suspected Iran of funneling weapons for some time to Houthi rebels in Yemen, but now, U.S. Vice Adm. Kevin M. Donegan has confirmed that not only is Tehran smuggling weapons into the country, they are increasingly lethal and are both widening and prolonging the conflict.

Included are longer-range, more accurate missiles that Iran-backed rebels have fired into neighboring Saudi Arabia, which is leading a coalition of nations in a campaign in support of the government of President Abdrabbuh Mansur Hadi. Iran, meanwhile, backs the Houthi militia and loyalists of the former President of Yemen, Ali Abdullah Saleh.

Donegan, who is completing a two-year tour as commander of the U.S. Navy’s Fifth Fleet, based in Bahrain, told The New York Times that Iran is providing increasingly lethal anti-ship and ballistic missiles, as well as sea mines and even explosive boats that have already been used to attack allied ships.

“These types of weapons did not exist in Yemen before the conflict,” said Admiral Donegan. “It’s not rocket science to conclude that the Houthis are getting not only these systems but likely training and advice and assistance in how to use them.”

Donegan’s allegations are supported, in part, by a November 2016 report by Conflict Armament Research, a private arms consultancy, which concluded that there is evidence of a “weapon pipeline, extending from Iran to Somalia and Yemen, which involves the transfer, by dhow, of significant quantities of Iranian-manufactured weapons and weapons that plausibly derive from Iranian stockpiles.”

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