Airstrikes attributed to a US-British coalition hit port cities and small towns in western Yemen on Monday, killing at least 11 people and injuring 14 while defending commercial shipping, a spokesperson for Yemen’s internationally recognized government told Reuters.

At least 17 airstrikes were reported in the country, including in the principal port city of Hodeidah and at Ras Issa Port, according to Al Masirah, the main Houthi-run television news outlet.

The strikes come just days after the first civilian fatalities and vessel loss since the Iran-aligned Houthis began attacking commercial shipping in November in solidarity with the Palestinians under attack by Israel.

The strikes also coincide with the first day of the Islamic holy month of Ramadan, a period of fasting for Muslims.

Despite reprisals from the US-British coalition and other navies, the Houthis have escalated their campaign of attacks on commercial vessels in one of the world’s busiest shipping lanes.

The Houthis killed three crew of the Barbados-flagged, Greek-operated True Confidence on Wednesday in an attack off the port of Aden.

That came days after the sinking of the cargo ship Rubymar, which went down about two weeks after being hit by a Houthi missile on 18 February.

Many ships are now making the longer, more expensive trip around Africa’s Cape of Good Hope to avoid the dangerous route through the Gulf of Aden and the Red Sea to the Suez Canal – sharply raising shipping costs.