It is a war you rarely see, but one that defines the US' relationship with Iran and Saudi Arabia in the Middle East.
Rare images from inside Yemen's city of Taiz show the devastation wrought by months of fighting between Houthi forces backed by Iran and Yemeni government forces, bolstered by Saudi Arabia and its US-equipped air power. They also expose the startling levels of hunger and disease in a conflict that so often goes unseen, even though a child under the age of five dies of preventable causes every 10 minutes.
The fight in Taiz has led to a slow victory for the Saudi-backed Yemeni government forces, but at a great cost to the city and its inhabitants.
Startling drone footage by Brazilian photographer Gabriel Chaim shows how barely a wall has escaped the force of Saudi air power, and at times Houthi shelling too.
Mayhoub, a US aid worker from Washington, DC, set up a charity in Taiz after finding himself trapped in the city by the war when visiting his sick mother. He happened to be in hospital when he saw an eight-year-old girl come in with horrific injuries from shelling.
"A little girl came into the hospital with her heart out," Mayhoub told CNN, without giving his full name as aid workers are often targeted in Taiz. "And you could see her heart pumping. It's inhumane. Who sends shells into the most heavily crowded city in Yemen?"
Mayhoub led Chaim, the photographer, around the city, explaining where the Houthis retained positions from where they could shell Taiz. The conflict in the city has been further complicated as the Houthis' enemies have begun fighting among themselves, making a reprieve in the violence even less likely.
The impact on the youngest Yemenis is also acute, as images from Camp al Mahu -- a haven near Lahj -- devastatingly show. Here, tiny nine-year-old Mailiki Seif weighs just 2 kilograms, reduced to twigs of bone. Her mother, Mariam, says this is actually an improvement.
"When we came here as displaced people, there was nothing wrong with her," she said, cradling her daughter's fragile frame. "Then she started to have measles, diarrhea and vomiting. She got very skinny." Only emergency rations have kept the little girl alive.
Mariam said she is from the Red Sea city of Mokha, but airstrikes forced her family to flee. Her husband's brother and son were among 25 people who died in a strike.
"They were hit by a jet in the market. The airstrikes were hitting very close to our home." She said they fled to the camp "because there is war everywhere except for here."
Only the pro-government Yemeni forces benefit from the backing of an air force -- usually Saudi but sometimes from the United Arab Emirates.
The Saudi air force has been accused of causing hundreds of civilian casualties in their intensive bombardment of Houthi-controlled areas.
The country and its allies back the internationally recognized Yemeni government and has imposed blockades on the parts of the country several times, hampering the delivery of aid.
More than 10,000 civilians have died and 40,000 have been wounded in the war, which has left 15 million Yemenis without access to clean water.
Saudi Arabia denies targeting civilians and rejected a UN report last year that blacklisted the country for deaths and injuries to children in the Yemen war.
The toll on the country's civilians has brought the US' support for the Saudis into question. In a recent admission of how deep and blind the US assistance to the Saudi air force is, US Central Command chief Gen. Joseph Votel said that while US fuel transport provides mid-air refueling for Saudi jets, they are not able to say which targets those jets go on to bomb.
During recent congressional testimony, Senator Elizabeth Warren asked if the US military was -- when it gets credible reports that civilians were killed in Saudi airstrikes -- "able to tell if US fuel or US munitions were used in that strike?"
Votel replied: "No, Senator, I don't believe we are."