The US and a host of other nations are creating a new force to protect ships transiting the Red Sea that have come under attack by drones and ballistic missiles fired from Houthi-controlled areas of Yemen, Defense Secretary Lloyd Austin announced Tuesday in Bahrain, Report informs via The Associated Press.

The seriousness of the attacks, several of which have damaged the vessels, has led multiple shipping companies to order their ships to hold in place and not enter the Bab el-Mandeb Strait until the security situation can be addressed.

The US military’s Central Command reported two more of the attacks on commercial vessels Monday. A strike by attack drone and ballistic missile hit a tanker off Yemen, at roughly the same time a cargo ship reported an explosive detonating in the water near them, the military said.

“This is an international challenge that demands collective action,” Defense Secretary Lloyd Austin said in statement released just after midnight in Bahrain. “Therefore today I am announcing the establishment of Operation Prosperity Guardian, an important new multinational security initiative.”

There are about 400 commercial vessels in the southern Red Sea, an area roughly the size of Washington D.C. to Boston, at any given time, a senior military official told reporters traveling in Bahrain with Austin. Under the new mission, the military ships that have increased their presence in the region will not necessarily escort a specific vessel, but position the military ships to be able to provide umbrella protection to as many as possible at a given time, the official said on the condition of anonymity to provide additional details that had not been made public on how the new mission will work.

In the last four weeks, Houthi militants have attacked or seized commercial ships 12 times, and still hold 25 members of the MV Galaxy Leader hostage in Yemen, Austin said in remarks Tuesday in a ministerial meeting on the new maritime mission. The US is still actively seeking member countries to join the mission, and increase the number of navies present and participating.

The United Kingdom, Bahrain, Canada, France, Italy, Netherlands, Norway, Seychelles and Spain have joined, Austin said. Some of those countries will conduct joint patrols while others provide intelligence support in the southern Red Sea and the Gulf of Aden.

One notably absent participant is China, which has warships in the region, but those ships have not responded to previous calls for assistance by commercial vessels, even though some of the ships attacked have had ties to Hong Kong, the military official said.

Several other countries have also agreed to be involved in the operation but prefer not to be publicly named, a defense official said on the condition of anonymity to discuss additional details of the new mission that have not been publicly announced.

The mission will be coordinated by the already existing Combined Task Force 153, which was set up in April 2022 to improve maritime security in the Red Sea, Bab el-Mandeb and the Gulf of Aden. While the task force has primarily provided a headquarters structure to date, the goal of the new mission is to generate ships and other assets to carry out the protection. There have been 39 member nations in CTF 153, but officials were working to determine which of them would participate in this latest effort.

Separately, the United States has also called on the United Nations Security Council to take action against the attacks.

In a letter to council members obtained Monday by The Associated Press, US Ambassador Linda Thomas-Greenfield said Houthi attacks targeting commercial vessels legally transiting the international waterways continue to threaten “navigational rights and freedoms, international maritime security, and international commerce.”

The 15 council members discussed the Houthi threat behind closed doors Monday but took no immediate action.

Two US warships — the USS Carney and the USS Mason, Navy destroyers — have been moving through the Bab el-Mandeb Strait daily to help deter and respond to attacks from the Houthis.

The move to set up the expanded operation came after three commercial vessels were struck by missiles fired by Iranian-back Houthis in Yemen on Dec. 3. Those attacks were part of an escalating campaign of violence that also included armed and other drones launched in the direction of US warships.

To date the US has not struck back at the Iranian-back Houthis operating in Yemen or targeted any of the militants’ weapons or other sites. On Monday Austin did not answer a question as to why the Pentagon had not conducted a counterstrike.