A ceasefire after weeks of Saudi-led coalition bombing in Yemen began on Tuesday night, but the coalition warned Iran-backed rebels it would strike back at any violation.
"Absolutely. 11 O'clock", coalition spokesman Brigadier General Ahmed al-Assiri said when asked whether the ceasefire had begun on schedule at 11:00 pm local time (2000 GMT).
"We are committed to respect this," he said, but the coalition will continue its "intelligence, reconnaissance and surveillance" in case it has to respond.
"We will be ready to react to any violation of the pause," he told AFP. "We are very clear. If they do not respect... we will continue."
The coalition intensified its air strikes, conducting a record of more than 130 sorties from Friday to Saturday, after declaring the rebels had crossed a "red line" with deadly mortar and rocket bombardments of Saudi Arabia.
Those attacks have killed 12 people on the Saudi side of the frontier since last week.
Assiri did not yet have any data on the number of sorties carried out on Tuesday in the leadup to the ceasefire.
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He said rebels fired several Katyusha rockets over the border on Tuesday, causing injuries.
Using unmanned aerial vehicles and artillery, coalition forces hit back and destroyed the vehicles which launched the rockets, he said.
A maritime exclusion zone, enforced by the Arab-dominated coalition, remains in effect around Yemen. Assiri said an Iranian ship purportedly carrying aid to Yemen should deliver it to the Horn of Africa nation of Djibouti.
"They can give it to the United Nations there," he said.
The Pentagon earlier said it was tracking the ship after Tehran reportedly said it would send warships to escort it to Yemen.
Pentagon spokesman Colonel Steven Warren warned Iran against a "stunt" that could threaten the ceasefire.
Frederic Wehrey, a senior associate in the Middle East programme at the Carnegie Endowment for International Peace in Washington, told AFP it is difficult to say if the ceasefire will hold.
"It's an issue of command and control and all it takes is one aggressive battalion commander to undo it," said Wehrey, a US Air Force veteran.