Chaos in Yemen has left the US military unable to monitor the vast arsenal it has spent years providing to its Yemeni counterpart. Yemen is now functionally leaderless after Houthi rebels took over the capital of Sana’a last month, prompting the resignation of President Abd Rabbo Mansour Hadi. The rebels are said to control the Yemeni military’s arms depots and bases, giving them effective control of US-provided and other heavy weaponry, including tanks and artillery. The unrest has “limited our ability to conduct routine end-use monitoring checks and inspections we would normally perform”, a US defense official told the Guardian....