They support Palestinians in Gaza. But what do Yemen's Houthi rebels really want?

They have no navy or air force. Their leader has a reputation for living on the move, shuffling between safe houses. And they emerged from a minority Shiite Muslim community in north Yemen’s rugged mountains in the ninth century.

Yet, this seemingly mysterious and hard-to-define group − the Houthis − has been fighting for control of Yemen for more than a thousand years. And now, they have managed to take on the overwhelming military might of the U.S., Britain and their powerful Western allies.

Since November, Iran-linked Houthi rebels have conducted dozens of missile and drone attacks on ships traveling in the Red Sea commercial waterway, a key trade route. The Houthis have sporadically attacked ships in these waters for years, but the attacks have spiked since the start of the war between Israel and Hamas. Those increased attacks have prompted a growing number of U.S.-led strikes against Houthi targets including radars, runways, missile launch sites and logistics hubs.

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The Houthis have directly connected their increased attacks to Israel's military campaign in Gaza and the skyrocketing Palestinian death toll. Their self-professed aim is to pressure Israel to stop the assault on Gaza that began after the October 7 Hamas attack. But Yemen experts say there is more to it than this.

So, who are the Houthis and what do they actually want?

Aligned with Iran − but only when its suits their interests

Yemen specialists say the Houthis are a political movement, a military force and a religious group. They have been fighting in a civil war in Yemen since 2014 against a fledgling government that is backed militarily by Saudi Arabia, the United Arab Emirates and − indirectly, through weapons supplies − the U.S. and Britain.

The Houthi ideology and political platform is vague and contradictory, according to Gregory Johnsen, a fellow at the Arab Gulf States Institute in Washington who studied and lived in Yemen for several years.

In an X thread, Johnsen said that beyond their stated reasons of defending Palestinians against Israel's onslaught in Gaza, the Houthis are seeking to exploit their attacks on Red Sea ships for their own political and economic ends.

"Politically, the Houthis need a rally-around-the-flag to mute what had been growing domestic discontent," he said. "Economically, the Houthis want to expand the local war in Yemen, because eventually they need to take either Marib or Shabwa (where Yemen’s oil and gas fields are) in order to have an economic base to survive long term in Yemen."

Military experts say that the Houthis' ability to target ships in the Red Sea would not be possible without Iran, which has supplied the group with sophisticated drones, and longer-range ballistic and cruise missiles.

Resenting U.S. troops in the Middle East, resenting American support for Israel

Like Iran, the Houthis resent the presence of U.S. troops in the Middle East and American support for Israel. In the wake of the U.S. invasion of Iraq in 2003, the Houthis adopted the slogan, "God is great, death to the U.S., death to Israel, curse the Jews, and victory for Islam." It borrows heavily from a similar slogan used by Iran.

Still, Helen Lackner, a veteran London-based independent researcher on the Middle East who focuses on Yemen, said that "the Houthis are aligned with Iran − but only if it suits their own interests."

Lackner said the Houthis should be understood as independent group who take advantage of what Iran can provide in terms of weapons, propaganda and a political alliance that opposes the U.S. and Israel.

At the moment, she said, Houthi "decisions fit in neatly with" Iran's agenda.

Transforming a ragtag militia a force capable of challenging world powers

In order to fully understand the Houthi movement, it's important to know that it is rooted in Zaydi Islam, a Shiite branch of the religion that believes they should only be ruled by imams with a very particular line of descent from the Prophet Mohammad.

One of the distinguishing features of Zaydi Islam is that its followers have a commitment to fighting corruption and pursuing religious scholarship. This helps explain their religious fervor and, to a degree, the mindset of the current Houthi leader.

Abdul Malik al-Houthi took over as the Houthi leader from his brother in 2004 when Hussein al-Houthi was killed by Yemen government troops, according to the Counter Extremism Project, an organization that tracks extremist ideologies.

He is thought be 42 or 44 and is known for being a fierce battlefield commander who transformed a ragtag militia located in Yemen's northern mountainous regions into a fighting force that appears to believe itself capable of challenging world powers.

Al-Houthi is also something of an enigma. Many of his speeches are pre-recorded. He rarely appears in public because of fears he could be assassinated.

Believing in the Palestinian cause, with the ultimate goal of destroying America

Maysaa Shuja Al-Deen, a Yemen-born researcher at the Sana'a Center for Strategic Studies, said that when high-level foreign officials travel to Yemen, they often don't actually get to see Al-Houthi in person. Instead, they are taken to secret locations where he appears for meetings by video link.

She said Al-Houthi's ultimate mission for the Houthis is to "revive the legacy of his ancestors," a project she described as installing a Zaydi imamate, a type of Shiite theocratic system. Al-Houthi also wants to stop what he sees as the spread in Yemen of Sunni Salafi groups, part of Islam's rival branch.

Elisabeth Kendall, a University of Cambridge professor who specializes in the Arab world, recently told Britain's Parliament in a foreign affairs committee hearing that increasingly Al-Houthi "speaks as though he's the word of God."

On top of all this, he strongly opposes foreign influence on Yemen's government.

"He believes in the cause of the Palestinians.'' Al-Deen said. ''But his ultimate goal is to defeat the Americans''' military presence and political influence in the wider Middle East region.

'A combination of the Taliban, North Korea and FARC'

Farea Al-Muslimi, a Yemen-born research fellow at Chatham House, a London think tank, said the recent wave of U.S. and U.K. retaliatory strikes on Houthis aimed at deterring their attacks in the Red Sea are unlikely to work. If anything, he said, the group will seek to expand its attacks across the Arabian Peninsula.

Al-Muslimi described the Houthis as a "combination of the Taliban, North Korea and FARC." FARC is a Marxist rebel group in Colombia.

Some U.S. military commanders have said the Houthis are nimble at irregular warfare. Al-Muslimi said that the Houthis "are savvier, more prepared and more equipped (militarily) than anyone is really acknowledging."

This may explain why the Houthis don't appear to be backing down in the face of the U.S.-led strikes. And how they've survived an estimated 25,000 air strikes by a Saudi-led coalition as part of Yemen's long-running civil war.

Kendall, Lackner and other Yemen experts say that there's no question that the Houthis believe in supporting the Palestinians in Gaza. They said this is a genuine motivation for the shipping attacks. However, they note that the attacks are also consistent with the Houthis' desire to portray themselves as a major regional player.

The attacks also serve, Lackner and others say, the Houthis' broader ideological purpose of lining up, with Iran, against the U.S. and Israel.

'Skyrocketing' popularity for supporting the Palestinian cause

However, something else explains what the Houthis want. And it has little to do with Iran.

"The Houthis are not very popular in the parts of the country they control, which covers about two-thirds of Yemen's population," said Lackner. "But the population in Yemen − everywhere − is very pro-Palestinian. Since the Houthis have been undertaking these attacks in the Red Sea their popularity has skyrocketed."

In fact, Lackner said, the attacks have "transformed" the Houthis' political position in Yemen − "from being disliked to actual heroes" in a country where the civil war has created the world's worst humanitarian crisis and basic services have collapsed.

The Houthis took over Yemen's capital Sana'a and several major ports in 2014, demanding lower fuel prices and a change of government. Still, despite their apparent repudiation of corruption, Al-Deen, of the Sana'a Center, said one of the things people in Yemen dislike about the Houthis is their constant demands for taxes for nothing in return.

"No salaries, no services, nothing, just nothing," she said.

Lackner noted their transformation has not been confined to Yemen or the Middle East.

"Yemen, Yemen, make us proud! Turn another ship around!" pro-Palestinian protesters chanted during a pro-Palestinian protest in New York City late last year.

"If you go to pro-Palestinian demonstrations now in England, you'll see signs saying, 'stop bombing Yemen' and people talking about the Houthis," she said.

"These guys didn't even know who the Houthis were a year ago."

This article originally appeared on USA TODAY: Why the Houthis are really attacking ships in the Red Sea