SANNA: Wth a "green light" from the Trump administration and essential military support from the USinfo-icon government, Saudi-led forces plowed ahead with an assault on the Yemeni port city of Hodeida on Wednesday, brushing aside dire warnings from international humanitarian organizations that an attack on the key aid harbor could spark a full-blown famine and endanger millions of lives.

Responding to the early stages of the attack--which began with an estimated 30 Saudi airstrikes within half an hour, guided by US military intelligence--"Win Without Warinfo-icon" wrote on Twitterinfo-icon that the attack is "a dark moment of shame for the United Statesinfo-icon. We could have stopped this."

Saudi mediainfo-icon reported that bombing of Iraninfo-icon-backed Houthi positions in the suburbs of Seham and Qazabah began around dawn on Wednesday and Saudi and UAEinfo-icon ships are now positioned just south of the city. 

Saudi-owned news channels and later state media said the battle had begun, citing military sources, a development later acknowledged by Ansarullah-run Al-Masirah news. 

The Houthi movement has pledged strong resistance in the face of the assault, which is said to be the largest of its kind since the onset of the war in early 2015.

Wall Street Journal reported, the U.S. military was providing its Gulf allies with intelligence to fine-tune their list of airstrike targets in Yemen's most important port, one sign of the Trump administration's deepening role in a looming assault that the United Nationsinfo-icon says could trigger a massive humanitarian crisis.

Aid agenciesinfo-icon are worried the fighting could destroy Hodeidah's port, a vital lifeline for Yemen through which more than 70 per cent of the country's foodinfo-icon supplies, goods and aids flow.  

Hodeidah is currently home to around 600,000 civilians, and around 80 percent of all humanitarian aid that flows into Yemen arrives at the city's port, which is currently controlled by Houthi Ansarullah movement. International observers have warned that a military fight over the port city could halt life-saving food and medicine and cause the starvation of millions.

"There are 11 million children in need of humanitarian aid in this war-torn country. Choking off this lifeline will have devastating consequences for every one of them," Unicef executive director Henrietta Fore said in a statement on Tuesday night. 

"Without food imports, one of the worldinfo-icon's worst malnutrition crises will only worsen. Without fuel imports, critical for water pumping, people's access to drinking water will shrink further. 

"Unicef teams delivered antibiotics, syringes, IV fluid, ready-to-use therapeutic food and hygiene kits to our local partners in Hodeidah just two days ago. But this will only last so long. Should the security situation worsen, our capacity to respond will be severely hampered."

Almost eight million Yemenis are already on the brink of famine and any hold up in supplies could send hundreds of thousands more sliding into hunger. 

The battle itself is expected to be the biggest of Yemen's three-year-war to date. Urban fighting could endanger the lives of up to 250,000 people, the UN warned last week.

Devastation on the ground in Yemen displayed by International Rescue Committee in shocking video

The Houthis are expected to withdraw to the mountains surrounding the city, but have promised to give the coalition "hell on hell" beforehand. 

Efforts from the UN's special envoy to Yemen, Martin Griffiths, urging all parties to accept a deal in which control of Hoidedah's port is given to the UN appeared to fail after a 48-hour deadline imposed by the UAE expired in the early hours of Wednesday. 

The UN and other aid organisations pulled their international staff from Hodeidah over the weekend after warnings from UKinfo-icon government sources diplomatic efforts would not succeed.  

Yemen's complex war has killed at least 10,000 people and left two thirds of the 28 million strong population dependent on aid. 

Seized by the Houthis in 2015, humanitarian organisations say the Saudi-led coalition blockade on Hodeidah is largely responsible for the intertwined malnutrition, healthcare and cholera crises. 

Previous diplomatic efforts from Western partners - many of which sell arms to Saudi Arabiainfo-icon and the UAE that rights groups say are destined for use in Yemen - have succeeded in delaying the offensive.

In recent months, however, there has been less and less appetite from the US to stand in the way of Saudi and UAE military policy in the devastating conflictinfo-icon.

Fears of humanitarian catastrophe

Jolien Veldwijk, acting director for Care International in Yemen said that the port of Hudaida is crucial for aid agencies to be able to do their work. 

"More than two-thirds of the people of Yemen count on the food that is imported through the port of Hudaida," Veldwijk said. 

"Even before the offensive on Hudaida started, already eight million Yemenis were at risk of famine and we really expect this number to increase rapidly, even if the port is closed for one day." 

Red Cross renews warning

On Wednesday, the UN and the International Committee of the Red Cross (ICRC) called on all sides to the Yemen conflict to protect civilians, voicing concerns about the humanitarian situation in Hudaydah.

"Under international humanitarian law, parties to the conflict have to do everything possible to protect civilians and ensure they have access to the assistance they need to survive," Lise Grande, UN humanitarian coordinator for Yemen, told Reuters.

 ICRC spokeswoman Marie-Claire Feghali also warned that the assault on Hudaydah was "likely to exacerbate an already catastrophic humanitarian situation in Yemen."