CNN –
The Biden administration is struggling to stop the Iran-backed Houthis' ongoing attacks on ships in the Red Sea, and the group continues to build up its weapons stockpile in Yemen, even as the U.S. has carried out significant attacks on the group in recent weeks, said US officials told CNN.
“We know that the Houthis have a large arsenal,” Pentagon deputy press secretary Sabrina Singh said Thursday, hours after the Houthis attacked another cargo ship in the Gulf of Aden with ballistic missiles. “They are very capable, they have sophisticated weapons, and that’s because they continue to get them from Iran.”
U.S. officials have wrestled with how to increase pressure on the Houthis, with some within the government arguing that the use of force alone does not work. Some officials also note that continuing to fire multimillion-dollar missiles at cheap Houthi drones and missiles is extremely expensive and impractical.
Outside the government, some former officials argue that the government has taken an overall too conservative approach and needs to focus on attacks on Houthi leaders rather than their weapons stockpiles.
The U.S. strategy for confronting the Houthis has changed since the attacks began in October in that U.S. Central Command has begun regularly pre-emptively targeting Houthi weapons in Yemen when the U.S. can detect systems being prepared to launch them .
However, several officials told CNN that the US still does not have a “denominator” that would allow them to estimate the percentage of Houthi equipment that they have actually destroyed, and it is not clear whether the US is changing its military approach would continue to change.
“They continue to surprise us,” a senior defense official said, referring to the Houthis. “We just don’t have a clear idea of what they have left.”
While the U.S. has struck dozens of Houthi targets in Yemen since January – including command and control nodes and weapons depots – the Houthis, in turn, are digging in, officials say, building tunnels near Yemen's west coast and staying underground more regularly.
Some within the government consider it a positive sign that the Houthis appear to be spending more time underground between attacks – forcing them into hiding, suggesting that the military strikes are having at least a psychological impact.
The Houthis are also extremely worried about their leadership being targeted in an attack and have become increasingly paranoid, two officials said.
For some former US officials who spoke to CNN on condition of anonymity, the fact that the US has not yet attacked the Houthi leadership and has instead focused on destroying weapons and equipment is a key reason why the US failed to effectively deter the group.
“The U.S. campaign against the Houthis appears to bear the hallmarks of many of those strictly limited, scrubbed campaigns of the past in which we try to avoid inflicting real pain on them,” a former U.S. military official said.
Former officials point to the administration's apparent success in deterring Iran-backed militias in Iraq and Syria by attacking their leaders. After those militants killed three Americans in Jordan in January, the U.S. carried out an attack in Baghdad on February 7 that killed two key militia commanders. The attacks have now stopped completely, the Pentagon said. Officials also believe that after the U.S. strikes, Iran ordered the groups to stop attacks.
The problem is becoming increasingly acute, especially given the significant increase in Houthi attacks in the last two days. The Houthis' first use of an unmanned underwater drone last week also alarmed US officials.
This drone was ultimately destroyed by US forces. But unmanned surface and underwater vessels are “more of an unknown threat” that could be “extremely deadly,” Rear Adm. Marc Miguez, the commander of Carrier Strike Group 2, told CNN last week. He said the U.S. had “very little confidence in any stockpile that the Houthis have of such weapons.”
It is also unclear whether the Biden administration could meaningfully increase its military actions against Houthi targets, particularly to target Houthi leaders in Yemen, without first addressing some of the outstanding questions surrounding the legality of the campaign. Some lawmakers on Capitol Hill have questioned whether the Biden administration would need congressional authorization to continue the campaign beyond the 60-day deadline set by the 1973 War Powers Resolution. In theory, that 60-day period could expire on March 12, two months after the government's first major attacks in Yemen.
Some argue that the US must now move to a stronger international pressure campaign and better highlight how the attacks are hindering humanitarian aid deliveries to vulnerable populations – including people in Yemen.
The Houthis are deeply concerned about their public image at home, officials said, and have sought to portray themselves as scrappy outsiders fighting to improve the lives of Palestinians and end Israel's war in Gaza. While the Houthis are not very popular in the areas of Yemen they control, the Palestinian cause itself is popular among Yemenis, officials noted.
At the same time, the Houthis also longed for international legitimacy, officials said, and wanted to be recognized as Yemen's official government. To do this, they have been fighting for years as part of a civil war against a Saudi coalition that supports the internationally recognized government of Yemen.
Some senior officials within the government therefore believe that if Israel ended its war in Gaza, the Houthis would keep their word and stop their attacks, which some former officials privately describe as wishful thinking.
Publicly, the government has repeatedly downplayed Houthis' claims that they were attacking ships to pressure Israel into a ceasefire, stressing that most of the targets had no ties to Israel or its allies.
Privately, however, some senior officials acknowledge that it is entirely possible that the Houthis will stop if Israel does so – and they point to the fact that the Houthi attacks in November largely occurred during a seven-day lull in fighting between Israel and Hamas subsided.
Still, officials say they can't wait to see if a ceasefire is reached to respond to the Houthis' aggression. The State Department and Pentagon have therefore worked to further incite both ordinary Yemenis and the international community against them, and this week began more forcefully challenging the militants' narrative.
State Department spokesman Matthew Miller and the Pentagon's Singh both pointed to a Houthi attack on a ship carrying corn and other food to the Yemeni people in Aden, and Singh pointed out that another ship was hit by a missile and is currently sinking into the Red Sea transporting fertilizers and now poses a significant environmental risk to the region.
“The Houthis are creating an environmental threat right on their own doorstep,” Singh said Thursday. “They say they are carrying out these attacks against ships linked to Israel. These are ships that are literally bringing goods, services and aid to their own people and creating their own international problem.”
A key aspect of this international pressure campaign is the support of the United States' Arab allies. The US has managed to attract some key regional partners to the Red Sea merchant shipping defense operation, known as Operation Prosperity Guardian, including Oman and Bahrain.
But officials say more needs to be done to convey to the Houthis that they are becoming a pariah on the world stage. Even Iran, which has long supported the Houthis but lacks perfect leadership and control over them, is increasingly concerned about the rebels' tactics, as CNN previously reported.
Still, there are no signs yet that Iran is actively denying support to the Houthis, officials said. The US has continued to ban Iranian arms shipments to Houthi-controlled areas in Yemen, including earlier this month.