Fighting has broken out in the streets of Yemen's key port Hodeidah between Iran-backed Houthi rebels and Saudi-led coalition forces.
A pro-Yemeni military official said Sunday the forces aim to "purge" the city of the rebels, who control the port, where nearly all food, medicine, and other supplies for civilians are delivered.
Humanitarian workers fear a disruption of those deliveries could mean mass starvation in a country already on the brink of famine.
The Saudis accuse the Houthis of using the port to take deliveries of Iran-supplied weapons - a charge Tehran denies.
Reports say at least seven civilians have been killed in the street fighting.
"We hear loud shelling and they are using all kinds of weapons. It is terrifying," one Hodeidah resident said Sunday. "Apache helicopters are bombing Houthi positions all day long."
Some Yemenis reported seeing snipers on rooftops throughout the city.
Others fear for the safety of patients in a Hodeidah hospital which is surrounded by rebel fighters.
A number of top officials with the former Obama administration are calling on the Trump White House to cut off all support for the Saudi coalition in Yemen.
Both Secretary of State Mike Pompeo and Defense Secretary Jim Mattis have called for a cease-fire by the end of the month.
U.S. State Department spokesperson Heather Nauert said in a statement Sunday that Pompeo spoke with Saudi Crown Prince Mohammed bin Salman about Yemen.
"The secretary reiterated the United States’ calls for a cessation of hostilities and for all parties to come to the table to negotiate a peaceful solution to the conflict under the U.N. special envoy," the statement said.
The Trump administration has also said it will no longer take part in refueling operations for Saudi-led coalition aircraft involved in the fighting.
The United Nations is hoping for peace talks in Yemen by the end of the year.
The Houthis seized the capital of Sana'a in 2014, forcing the Yemeni government into temporary exile in Saudi Arabia. It has since relocated to Aden.
Saudi-led airstrikes on the rebels have obliterated entire civilian neighborhoods, including hospitals, and have compounded the misery in Yemen, which is also dealing with starvation and a cholera outbreak.