• U.S. military forces and allied nations attacked Houthi land targets over the weekend.
• The rebel army is undeterred, with attacks on ships in the Red Sea continuing, and one of the latest resulting in an 18-mile long oil slick.
• The European Commission is stepping up its efforts in the region as part of the EU Aspides naval defense effort, recently intercepting aerial drones coming from Yemen.
• Federal maritime officials in the U.S. tell CNBC they want more pressure placed on the government of Yemen to help stop the attacks.

The battle for the freedom of navigation in the Red Sea has expanded with the entrance of a European Commission naval defense effort in the past week, and more U.S. and allied strikes against Houthi land targets over the weekend, but to date, combined military efforts have not deterred rebel attacks.

On Saturday evening, United States Central Command reported that the USS Mason shot down one antiship ballistic missile launched into the Gulf of Aden from Iranian-backed Houthi-controlled areas of Yemen. Central Command said the missile was likely targeting the U.S.-flagged, owned, and operated chemical/oil tanker, MV Torm Thor. The ship was not damaged and there were no injuries. Defense officials tell CNBC as of February 21, there have been at least 59 attacks on commercial shipping interests in the Red Sea.

Last week, the European Union's Naval Force (EUNAVFOR) Operation Aspides, a EU defensive maritime security operation, joined the French Navy operation along with U.S.-led Operation Prosperity Guardian to protect the freedom of navigation for ships in the Red Sea. This is not the EU's first mission in protecting maritime trade, as it already patrols the waters off the Libyan Coast, around the Cape of Good Hope, and the Gulf. But the EU said the Red Sea moves reflect the need for a stronger European presence in protecting ships from Houthi attacks.

Unlike the U.S. and UK, which use both defensive measures to protect commercial vessels on the water and launch attacks on Houthi land targets, the Aspides operation is solely to protect vessels by intercepting Houthis drones and missiles. It will not escort vessels as the EU has done in anti-piracy measures off of Somalia, where pirates use small boats to gain entry onto a vessel, a tactic not used by the Houthis.

The European Commission naval operation is a complement to Operation Prosperity Guardian, Peter Stano, lead spokesman for European Commission's foreign affairs and security policy, told CNBC. The intelligence gathered by Aspides is being shared with both the French naval operation and OPG.

Josep Borrell, high representative for EU foreign affairs and security policy, who has launched seven missions for the EU Commission, described the launch of the defensive operation "as a fast and robust reaction to the behavior of the Houthis, who are attacking commercial ships in the region."

CNBC was told the four frigates and one aerial asset in this operation would be deployed to protect all assets the Houthis have been firing on, with all flagged commercial vessels offered protection.

"If the EU mission is well integrated with U.S. forces already present it would be a great thing," said U.S. Navy Rear Admiral (Ret.) Mark Montgomery, a senior fellow at the nonpartisan Foundation for Defense of Democracies who served as policy director for the Senate Armed Services Committee under Sen. John McCain. "This interoperability can easily be provided through the use NATO standard data links which are present on all these warships."

On Saturday, U.S. Central Command forces, alongside UK forces, and with support from Australia, Bahrain, Canada, Denmark, the Netherlands, and New Zealand, conducted strikes against 18 targets in Houthi-controlled areas of Yemen. These strikes are separate and distinct from Operation Prosperity Guardian.

Trade leaders have urged more countries to join the military effort in the Red Sea.

"It is so critical because of the immediate direct and adverse impact the Red Sea attacks have had on commerce destined to or being shipped from Europe," Steven Lamar, CEO of the American Apparel and Footwear Association, said of the stepped-up EU efforts. "But this is truly a global problem as disruption in the Red Sea/Suez Canal triggers a logistical butterfly effect that is rippling around the world. It is long past time for every country to align with these efforts so we can collectively maintain a zero-tolerance approach to stop and prevent attacks on seafarers, their cargo, and their equipment now and in the future."

A war of misinformation in the Red Sea crisis also continues. The Houthis have had a track record of making false claims with the declaration of the "sinking" of ships showing old, unrelated videos to augment their messaging.

The Houthis recently used video to make the claim they had sunk the Belize-flagged, UK-owned bulk carrier M/V Rubymar. The Rubymar did not sink, but the vessel was abandoned by the crew after the vessel started to take on water. U.S. Central Command released satellite photos of the vessel on Friday showing significant damage to the ship, which already had caused an 18-mile oil slick.

Central Command warned that the M/V Rubymar was transporting over 41,000 tons of fertilizer when it was attacked, which could spill into the Red Sea and worsen the environmental disaster.

As the EU increased its presence in the region last week, Houthi foreign ministry official Hussein al-Azzi said on Wednesday that the rebel army had "constructive talks" with the EU. Stano refuted the idea of any discussions between the EU and the group.

"The interpretation of EU outreach regarding the naval mission Aspides by Houthis is not accurate," he said. "The EU denies that it is coordinating with the Houthis for the safe passage of commercial ships through the Red Sea and is consistent in its condemnation of the Houthi attacks."

Stano said the attacks are a violation of international law, threatening maritime security, navigational freedoms and global trade, and putting the lives of sea crews at risk.

"They are also causing significant and unacceptable damage to trade, countries, and people in the region," he said. "They need to cease immediately, as reiterated in the UNSC Resolution 2722 adopted on January 10. This is a very clear message delivered consistently to the Houthis."

The only communication the European Commission has had with the Houthis is the open communication it has provided to the numerous countries in the region to provide clarity on the Aspides operation.

"The EU has been conducting an extensive diplomatic outreach to inform partners and relevant stakeholders about the mandate and objective of the new EU maritime operation Aspides, specifically insisting on its defensive nature and protection of freedom of navigation," Stano said.

On February 2 in Brussels, Borrell informed Yemeni Prime Minister Bin Mubarak about the plans to launch a new EU maritime operation in the Red Sea and about its mandate. The two also briefly discussed the situation in Yemen and longstanding EU support to the Presidential Leadership Council, Yemeni government and to the UN-led peace efforts.

"The EU Head of Delegation accredited to Yemen maintains regular exchanges with all Yemeni interlocutors, including the Houthi leadership," Stano said. "The EU reaffirms its principled commitment to the unity, sovereignty, independence, and territorial integrity of Yemen and its support to President Rashad Al-Alimi and the Presidential Leadership Council."

The role Yemen is playing in the crisis is the focus of a potential investigation in the United States, with Federal Maritime Commission Commissioner Carl Bentzel proposing an investigation into Yemen's inability to protect the Law of the Sea by not stopping the Houthis from attacking waters the country is obligated to protect under international maritime law. He told CNBC meetings are continuing to discuss a way forward to initiate the investigation.

A provision of the Foreign Shipping Act allows the federal government to launch an investigation of a foreign government's practices and consider the impact those actions have on global maritime trade.

"The longer these impacts linger, the greater the economic impact," Bentzel said. "We need an investigation to determine whether the actions emanating in Yemen cause unfavorable conditions to shipping in the foreign commerce."

If the Commission agrees and the investigation does proceed, the State Department could assist the FMC.

"From an economic perspective, Egypt alone can lose upwards of $5 billion this year in lost revenue as a result of the Suez Canal diversions. The Tesla factory in Germany was forced to close for a month," Bentzel said. "U.S.-flagged vessels have been attacked. Yemen has failed to secure innocent passage of their territorial waters or straits. If terrorists were shooting rockets at a truck carrying Walmart or Target retail goods because they were doing in business in Israel there would be outrage. I don't sense the same concern for maritime workers," he said.