"We should make no mistake, if the port is out of action, Yemeni citizens will die".
The initial battle plan appeared to involve a pincer movement.
Prince Khalid added in a separate tweet that the Saudi-led coalition's operations in Hodeidah are important in light of the increased threat the militias controlling the port have been posing for maritime security in the Red Sea.
Field commanders said that troops pushed towards Hodeida airport after Yemeni pro-government forces received a "green light" from the coalition. They spoke on condition of anonymity as they weren't authorised to brief journalists.
Urging worldwide organizations to adopt a serious stance against such an unprecedented assault on the Yemeni port, the official underlined that the Houthi Ansarullah Movement will keep assisting with the delivery of global humanitarian aid to Yemen, al-Masirah TV reported.
The Houthi-run Al Masirah satellite news channel claimed rebel forces hit a Saudi coalition ship near Hodeida with two missiles.
A Yemeni anti-Houthi military official said the alliance had brought to bear a 21,000-strong force. A Saudi-led coalition entered the conflict in March 2015.
Yemen's internationally recognised government earlier pronounced negotiations had failed to force the rebels from Hodeida, and a grace period for UN-led peace efforts was over.
The liberation of Hodeidah Port and the continuation of its operations effectively by the Yemeni General Authority for Transport along with the Saudi Ports Authority and its UAE counterpart would lead to the flow of more relief, food and commercial shipments. The work in the port is normal.
"A military attack or siege on Hodeidah will impact hundreds of thousands of innocent civilians", Lisa Grande, the U.N.'s humanitarian coordinator for Yemen, warned in a statement before the offensive began.
"It's one of the poorest governorates in Yemen, and it's also a very densely populated urban center", Hodeib said in a phone interview Wednesday.
The United Nations says 22 million Yemenis need humanitarian aid, and the number at risk of starvation could more than double to more than 18 million by year-end unless access improves.
Angela Merkel calls United States retraction of support 'sobering and somewhat depressing'
Trump then declared on Twitter that he no longer endorsed the statement. Trump's late arrival also highlighted his early departure. Trump reportedly missed Trudeau's opening remarks.
The Red Sea port, controlled by the Iran-backed Huthi rebels, serves as the entry point for 70 percent of the impoverished country's imports, but the coalition maintains that the rebels use it to smuggle weapons.
They say the fighting is raging in the coastal areas of ad-Durayhimi district.
United Nations refugee chief Filippo Grandi said there was a danger Yemenis might try to flee across the sea to Somalia or Djibouti.
"We hear sounds of explosions".
"Should we leave the Houthis smuggling missiles?"
It would be the first time since they joined the war on behalf of Yemen's exiled government that the foreign armies have attempted to capture such a well-defended major city.
Aid workers had similar worries. Four civilians were reportedly killed and at least two more injured in those airstrikes.
Aid groups have pulled staff from the town over the deteriorating security situation and warned of catastrophic consequences.
The new United Nations envoy to Yemen, Martin Griffiths, tweeted that he was "extremely concerned" by the violence, calling on all parties to exercise restraint.
He added that the UAE and the Saudi-led coalition went ahead with the campaign despite knowing that global aid agencies fear it could lead to a humanitarian crisis.
Get the Monitor stories you care about delivered to your inbox. Effort to kill Trump tariffs blocked Trump stokes confusion with pledge to halt Korean war games Five takeaways from Trump's summit with Kim Jong Un MORE and Secretary of State Mike PompeoMichael (Mike) Richard PompeoWith caveats, Republicans praise Trump's summit with Kim Jong Un Pavlich: Pompeo: The man for the job on North Korea Five takeaways from Trump's summit with Kim Jong Un MORE on the eve of the offensive expressing "grave alarm". The US has been offering targeting information to the Saudi-led coalition, as well as refueling their warplanes, though its role in Wednesday's assault wasn't immediately clear.