The United Nations and other aid groups already had pulled their global staff from Hodeidah before the rumoured assault.
Hodeidah, Yemen's biggest port and the only port controlled by the Houthis, serves as the lifeline for the majority of Yemen's population, which lives in Houthi-ruled territory.
A source from the Yemeni National Resistance said that a large number of forces from Brigades AlAmalaqah and the Tihama Resistance Forces, armed with modern weapons and in high morale, have arrived at the outskirts of Al Hodeidah city to continue their build-up in the front lines in preparation for the battle of rolling back the Houthi militias and putting and end to the coup plot in Yemen.
The United Nations had been trying to get the parties to reach a deal that would avert an attack on Hodeidah, which it fears would further impede Yemenis' access to food, fuel and medicine, exacerbating the world's most urgent humanitarian crisis in the impoverished Arab state.
The civil war in Yemen has killed about 10,000 people over the past three years and created what the United Nations says is the world's worst humanitarian disaster. The Saudi-led coalition has been criticized for its airstrikes killing civilians.
The UN says some 600,000 people live in and around Hudaida, and "as many as 250,000 people may lose everything - even their lives" in the assault.
Washington had also cautioned against the assault.
Defense Secretary Jim Mattis on Monday acknowledged the United States continues to provide support to the Saudi-led coalition.
The air strikes on Wednesday morning targeting Houthi positions are supported by ground operations by Yemeni troops south of the Red Sea port, the internationally recognised Yemeni government-in-exile said in a statement.
The Houthis, with roots in a Zaidi Shi'ite minority that ruled a thousand-year kingdom in Yemen until 1962, deny they are pawns of Iran.
Yemen lies beside the southern mouth of the Red Sea, one of the most important trade routes in the world for oil tankers, which pass near Yemen's shores while heading from the Middle East through the Suez Canal to Europe.
He said the coalition wanted the United Nations to take control of the port but it was prepared to take military action if the Houthis refused to withdraw.
Riyadh says the Houthis use the port to smuggle Iranian-made weapons, including missiles that have been launched at Saudi cities - accusations denied by the group and Tehran.
Twenty further runs in the final two overs took Pakistan past the 200-run mark, leaving Scotland with too much to chase. Australia know they must build bridges across the cricketing world in order to fix reputations and trust.
Mais il le sera nettement moins que lors de la précédente journée de mobilisation spéciale, la "Journée sans cheminots " le 14 mai, qui avait vu rebondir la participation jusqu'à frôler les 28% de grévistes.
But a White House official has since confirmed that the President has read the contents of that giant envelope. Frenetic meetings - Pompeo has scheduled a news conference on Thursday, at the end of his meetings with Kim.
More importantly, he would head to Shinnecock Hills with a spring in his step for the second major championship of the year. At the 445-yard par-4 sixth, Bryan got on in 2 and missed his par putt from 4 feet, finishing with a 3-putt bogey.
Le couple a un petit garçon, Edward Miller , né en 2015, un an avant Emeline , qui avait vu le jour en 2016. L'ancien skieur américain, champion olympique en 2010, a annoncé la mort d'Emmeline, sa fille de 19 mois .
L'Espagnol a parfaitement commencé et fini ce set, ne laissant que l'Autrichien l'accrocher en milieu de première manche. Nadal est resté imperturbable sur ses mises en jeu et s'est même permis de briser son adversaire (5-2).
But it's a challenge Gunther welcomes. "He's got such a natural high cruising speed and he can just kind of keep on going". If he stays in the east, Justify now goes on to either the Grade 1 Haskell at Monmouth Park or the Jim Dandy at Saratoga.
Coupe du Monde 2018 : "Je vais bien", assure Mbappé
Pour rappel, l'équipe de France débutera sa Coupe du monde face à l'Australie le samedi 16 juin à 12h. Mbappé a également pris la défense de son coéquipier Adil Rami qui l'a percuté lorsqu'il s'est blessé.