Maersk has sent two container ships through the Red Sea carrying goods for the United States military and government, according to the Danish company and ship tracking data.

Maersk and other large shipping lines have instructed hundreds of commercial vessels to stay clear of the Bab al-Mandab Strait near Yemen, sending vessels on the longer route around Africa in response to attacks on shipping by Iranian-backed Houthi militants.

The two U.S.-flagged vessels, Maersk Sentosa and Maersk Kensington, sailed from Salalah in Oman through the Bab al-Mandab Strait and were headed north through the Red Sea, according to LSEG ship-tracking data.

Both vessels passed the strait with their AIS tracking system turned off to avoid detection. The Maersk Kensington reappeared at 0818 GMT on Tuesday, while the Maersk Sentosa was seen to have switched on AIS at 2211 GMT on Monday, the data showed.

Maersk Sentosa and Kensington, with capacities of 6,500 and 6,200 twenty-foot containers, respectively, are part of Maersk Line Limited, a U.S. subsidiary of the Danish company.

With a fleet of 20 smaller container vessels, the unit ships goods for U.S. agencies including the Department of Defense, State Department and USAID, Maersk said.

“The few Maersk Line Limited-vessels making the crossing are doing so in the near proximity of U.S. Navy assets, which have reduced the risks to the crews and cargo,” Maersk said in an email to Reuters.

A U.S.-led coalition was established last month to safeguard commercial traffic in the Red Sea.

The U.S. and Britain launched dozens of air strikes against Houthi military targets in Yemen on Jan. 11 and Jan. 12 in retaliation for attacks on shipping by the Houthi militants.

Source: Reuters reported by Jacob Gronholt-Pedersen and edited by Jason Neely