The United States and Britain carried out another round of large-scale military strikes Saturday against multiple sites in Yemen controlled by Houthi militants, U.S. officials said.

The strikes were intended to degrade the Iran-backed militants’ ability to attack ships in sea lanes that are critical for global trade, a campaign they have carried out for almost four months.

U.S. and British warplanes hit missile systems and launchers and other targets, the officials said. Australia, Bahrain, Canada, Denmark, the Netherlands and New Zealand provided support for the operation, according to a joint statement from the countries involved that was emailed to reporters by the Defense Department.