A projectile launched from the Houthi rebel controlled area of Yemen struck a German-owned ship traveling through the Red Sea on Dec. 15, causing a fire. This is one of many recent attacks from the Houthis, which have escalated since the Israel-Hamas war. The militant group has vowed to attack all ships stopping at Israeli ports. As a result, some ships, including at least two Danish vessels from the shipping company Maersk have even opted to take alternative journeys across Southern Africa, a significantly longer trade route, in order to avoid the violence.

Who are the Houthi rebels?

The first iteration of the Houthis emerged with a group called the Believing Youth, who led a revivalist movement for the Zaydi branch of Islam in the 1990s. Many Zaydi muslims, who make up about 35% of the country, felt that the increasing presence of Saudi-influenced Salafi Islam was interfering with their cultural heritage and rights.

In 2004, the group evolved and came to be known as the Houthis after their leader Hussein al-Houthi was killed. It was also around this time that they began launching insurgencies against Yemen’s government.

“Some of their grievances against the government aligned with the grievances of other sectors of Yemeni society around government corruption and mismanagement, but they also had some specific grievances regarding perceived infringement on the cultural rights of Zaydi Muslims,” says Stacey Philbrick Yadav, the chair of international relations at Hobart and William Smith Colleges who published a book about Yemen’s war in January.

In 2011, grievances among the Yemeni over poor economic conditions and corruption boiled over into mass protests that eventually led to the ousting of Yemen’s president Ali Abdullah Saleh who had been in power for 34 years. The international community then tried to establish a transitional government for Yemen that excluded the Houthis, which led the Houthis to forcefully enter the capital of Yemen to demand inclusion in the government. The conflict intensified in 2015 when Houthi rebels aligned with former president Ali Abdullah Saleh against the internationally-backed government.

Saudi Arabia has been a leading force in the war against the Houthis. Because of this, the Houthis have grown more aligned with Iran. Nevertheless, Philbrick Yadav, who spoke to TIME over the phone, says that she wouldn’t go so far as to call them a direct Iranian proxy.

“They do have a relationship with and support from Iran, but are not a straightforward proxy of Iranian interests. They have their own locally defined interests and so I think that their actions in the past two months have reflected that,” she says.

In Yemen, supporting Palestinian people is an extremely popular opinion. Philbrick Yadav says that showing support for Palestine helps the Houthis gain popularity. “This is a way in which the Houthis can try to expand their appeal to Yemenis who don't support their domestic political project,” she says.

How relevant is the economic impact?

Over 80% of the world’s traded goods are transported via sea vessels, meaning that the annual shipping trade is worth over 14 trillion dollars, according to the International Chamber of Shipping, or 16% of global GDP.

Transporting items via sea is usually more cost effective than moving via air, meaning that the shipping industry is essential for transporting nearly every imported product we use—from clothing and cars to oil and gas.

The Red Sea directly feeds into the Suez Canal, the only water route available for ships traveling from Asia to Europe without having to sail around the African continent. Corey Ranslem, the CEO of Dryad Global, a prominent maritime security firm, says that traveling via the Suez Canal and Red Sea can save ships over 30 days in travel time.

“Depending on where the vessel is headed for its ultimate destination, to go around the Cape of Good Hope in Africa could be extremely expensive and time consuming, and you have pretty challenging weather conditions,” Ranslem tells TIME during a phone call. “But at the same time now, vessels transiting through this region of the Gulf of Aden and the Red Sea are also seeing their costs rise because insurance companies are continuing to increase premiums.”

According to Reuters, war risk premiums have risen from approximately 0.07% of the value of the ship last week to up to 0.2% the value of the ship this week. This can increase the cost of a single seven-day voyage by tens of thousands of dollars.

Which ships are being targeted?

The Houthis have publicly stated that they are targeting ships that they believe are stopping in Israel. So far, Ranslem says that most of the attacks have been targeted at ships that were planning to stop in either Ashdod or Haifa, prominent port cities in Israel.

Before the attacks, both ports had a list of ships expected to arrive over the next several weeks published online. Those lists have been taken down.

“Right now, any vessel that is transiting through this region that is heading to an Israeli port is at a much higher risk than other vessels,” says Ranslem.

However, Ranslem says that it is possible ships without planned stops in Israel could also be at risk. “With some of the recent events, we're seeing that vessels in general could be at risk as they're going through this particular region, but we are still evaluating that on a daily basis,” he notes.

U.S. National Security Advisor Jake Sullivan told reporters on Dec. 4 that the U.S. is working to build a coalition with partner nations to provide protection for global shipping in the region. However, it will likely take several weeks or months before any such plan can effectively provide protection, argues Ranslem. This means the ships seemingly remain at risk for now.

US weighs strike options to deter Houthis from more Red Sea attacks

Top Biden administration officials are actively weighing options to strike back at Houthis in Yemen after the Iran-backed group launched new attacks on naval and commercial ships in the Red Sea on Saturday, according to two U.S. officials.

The Pentagon has in recent days moved the Dwight D. Eisenhower Carrier Strike Group from the Persian Gulf into the Gulf of Aden, off the coast of Yemen, to support a potential U.S. response to attacks, said one of the officials, both of whom were granted anonymity to speak about sensitive plans. The military has also provided options to commanders to strike the Houthis, the official said.

The Biden administration has been reluctant to respond militarily against the Houthi attacks on commercial shipping in recent weeks for fear of provoking Iran, which backs Hamas and Hezbollah in Yemen as well as the Houthis. Previously, the Pentagon had recommended the administration not do so.

But a significant uptick in attacks in recent days could potentially lead top U.S. national security officials to change their calculus.

The destroyer USS Carney, operating in the Red Sea, shot down 14 one-way attack drones launched from Houthi-controlled territory in Yemen early Saturday morning. Meanwhile, a British destroyer, the HMS Diamond, which had recently arrived in the region to help protect commercial shipping, also shot down a Houthi drone.

On Friday, a Houthi drone struck the Liberian-flagged Motor Vessel Al Jasrah in the Red Sea, causing a fire. The same day, Houthi forces also launched two ballistic missiles toward the Bab el-Mandeb strait, one of which struck the Liberian-flagged Motor Vessel Palatium 3. U.S. warships responded to the attacks at the time.

A Pentagon spokesperson declined to comment on ongoing operations.

The assault has had a significant impact on the commercial market. Maersk, the world’s biggest shipping company, on Friday halted all shipping through the Bab el-Mandeb Strait, a vital passageway for cargo and energy shipments traveling between the Red Sea and the Gulf of Aden.

The news comes as Defense Secretary Lloyd Austin and Joint Chiefs Chair Gen. C.Q. Brown are set to travel to the Middle East this week. Austin is slated to huddle with leaders in Israel, Bahrain and Qatar; Brown will join Austin in Israel.

The Pentagon has bolstered its presence in the region, moving three additional destroyers into the Mediterranean Sea this week. The ships join the Gerald R. Ford Carrier Strike Group that has been operating in the Mediterranean since Hamas’ Oct. 7 attack on Israel, a deployment that Austin extended again this week.

Over the past week, missile-defense destroyers Laboon, Delbert D. Black and The Sullivans have arrived in the Mediterranean.

Houthis launch more attacks in Red Sea as US warships head to region

American and British warships shot down over a dozen drones launched from Houthi-controlled areas of Yemen on Saturday, the latest onslaught against naval vessels and commercial shipping in the Red Sea by the Iranian-led group.

The Carney, a U.S. destroyer, intercepted 14 “one-way attack drones” according to the U.S. Central Command while the British destroyer HMS Diamond, newly arrived in the region to bolster protection of commercial shipping, also shot down a Houthi drone.

The drone and ballistic missile attacks on commercial and military shipping caused Maersk, the world’s biggest shipping company, to instruct its vessels on Friday to “pause their journey until further notice” through the Bab el-Mandeb Strait in the Red Sea.

While the U.S. ships, Carney and fellow destroyer Mason, have been busy intercepting Houthi attacks in recent weeks, three more U.S. Navy destroyers have moved into the Mediterranean Sea over the past week as the U.S. beefs up its presence in the region.

The ships join the Gerald R. Ford Carrier Strike Group that has been operating in the Mediterranean since Hamas’ Oct. 7 attack on Israel, a deployment that has already been extended twice.

The Ford has its own two destroyers and cruiser escort and has been at the forefront of an expanding American presence in the region in the wake of Hamas’ attack and the subsequent Houthi ballistic missile and drone intercepts by American, French and British warships.

Over the past week, missile-defense destroyers Laboon, Delbert D. Black and The Sullivans have arrived in the Mediterranean to boost the U.S. presence there. Defense officials would not comment on if the ships are heading to the Red Sea.

In addition to Carney shooting down the drones on Saturday, on Dec. 13 the Mason shot down an unmanned aerial vehicle that U.S. officials said was launched from Yemen, the second time this month the U.S. warship has opened fire.

Just days earlier, the Mason came to the aid of a commercial ship after it was hit by a cruise missile in the Red Sea’s Bab-el-Mandeb strait. The Carney has also intercepted several drones and cruise missiles that U.S. officials said were flying in the vicinity of the ship.

The British HMS Diamond Saturday also destroyed a drone that was “targeting merchant shipping,” according to British Defense Minister Grant Shapps.

Shapps said attacks on commercial ships by Yemen’s Houthi rebels “represent a direct threat to international commerce and maritime security."

The increased deployments of ships and Houthi attacks come as Defense Secretary Lloyd Austin is slated to travel to the Middle East next week, as the Biden administration tries to respond to a spike in Iran-backed attacks on American forces in the region and contain the Israel-Hamas conflict.

Plans call for Austin to huddle with leaders in Bahrain, Qatar and Israel.

American troops in Iraq and Syria have also been targeted by Iranian-backed proxies over 90 times since mid-October, leading to American airstrikes against the groups and their facilities.

At sea, the Biden administration is working to form an international maritime task force to counter the Houthi attacks. The plan appears to be that the planned group would expand an existing coalition of 39 nations, Combined Task Force 153, which is focused on countering piracy and terrorism in the Red Sea, Bab el-Mandeb waterway and Gulf of Aden.

“We are definitely looking to take action here,” Pentagon spokesman Brig. Gen. Pat Ryder told reporters this month. “This is an international problem that requires an international solution.”

The head of the Oslo-based Norwegian Shipowners’ Association that tracks threats to commercial shipping across the globe, Harald Solberg, expressed deep concern over the threat to ships in the Red Sea.

“All attacks on commercial ships in this area, like the attack on the Norwegian product tanker MT Strinda this week, represent a deeply concerning development of the security situation for civilian shipping in the Red Sea,” he said. “Such attacks are serious and unacceptable, and we call upon all actors in the region to quickly de-risk the threat for civilian shipping in the area.”

“It must be a central priority to all governments involved to ensure that the world's most important supply lines are kept open.”

US military shoots down 14 Houthi attack drones targeting Israel.

Shipping companies abandon Red Sea routes over Houthi attacks.

British destroyer HMS Diamond has shot down a suspected "attack drone targeting merchant shipping in the Red Sea" during the night from Friday to Saturday.

That’s according to the country’s Minister of Defence Grant Shapps, who took to X - formerly Twitter - to share the announcement.

The Houthis have warned that they will target ships sailing off the coast of Yemen and with links to Israel, in response to the war between Israel and the Palestinian Islamist movement Hamas in the Gaza Strip.

In recent weeks, several missiles and drones have been shot down by American and French warships patrolling the area.

The United Kingdom announced at the end of November the dispatch of the warship HMS Diamond to the Gulf to respond to "growing concerns" on the security of maritime trade routes in the area.

Danish shipping giant Maersk on Friday ordered its ships to no longer pass through the strategic Bab al-Mandab Strait "until further notice" after new attacks.

The German shipowner Hapag-Lloyd also announced on Friday that it was suspending crossings of its container ships on the Red Sea at least until Monday after the attack on the Red Sea. one of its ships by the Houthis.

This political-military movement, which controls a large part of Yemen, belongs, like Palestinian Hamas and Lebanese Hezbollah, to what they call "the axis of resistance" against Israel, supported by Iran.