Yemen’s Houthi rebels said they targeted two ships sailing in the southern Red Sea on Tuesday. 

One of them, a small UK-run container ship called Morning Tide, had steel fragments on its deck this morning after an explosion about 50 or 60 meters away at 3:19 a.m. local time, according to the vessel’s owner, London-based Furadino Shipping Ltd. The militants said they also targeted the commodity carrier Star Nasia.

Since US and UK airstrikes on Yemen’s Houthi militants began last month, the group has stepped up attacks on merchant shipping with links to both nations. On Monday, the shipping industry warned there was a high risk of collateral damage for any vessel sailing through the region. The most significant incident so far was an attack on an oil tanker carrying Russian fuel that saw it catch fire, highlighting the risk of environmental disaster. 

US forces have been carrying out more strikes in Yemen over recent days, including on two Houthi sea drones that could have been deployed against commercial vessels and navy ships, US Central Command said on Monday night. 

Morning Tide is owned by London-based Furadino Shipping and Star Nasia is owned by Greece-based Star Bulk SA. 

A company official at Furadino said by WhatsApp that no crew were injured, the vessel suffered no damage, and was able to continue its route. The explosion “looked like fireworks,” the company official said.

A person answering the phone at Star Bulk said nobody was available to answer questions about the ship, and a follow-up email wasn’t immediately answered.