The US has called for a swift cessation of hostilities in Yemen, where three years of civil war have caused the world’s worst humanitarian crisis.
Defence Secretary James Mattis said all parties needed to take part in UN-led peace talks within the next 30 days.
Secretary of State Mike Pompeo meanwhile urged the Saudi-led coalition battling the rebel Houthi movement to end its air strikes on populated areas.
The US has faced growing pressure to end its support for the coalition.
UN human rights experts say coalition forces may have committed war crimes in Yemen and humanitarian organisations say their partial blockade of the country has helped push 14 million people to the brink of famine.
The murder of the US-based journalist Jamal Khashoggi by Saudi agents in Istanbul this month has also strained ties between Washington and Riyadh.
- Ending Yemen’s never-ending war
- Yemen crisis: Who is fighting whom?
Why is there a war in Yemen?
Yemen has been devastated by a conflict that escalated in early 2015, when the Houthis seized control of much of the west of the country and forced President Abdrabbuh Mansour Hadi to flee abroad.
Alarmed by the rise of a group they saw as an Iranian proxy, the UAE, Saudi Arabia and seven other Arab states intervened in an attempt to restore the government. They have received logistical and intelligence support from the US, UK and France.
At least 6,660 civilians have been killed and 10,560 injured in the fighting, according to the United Nations. Thousands more civilians have died from preventable causes, including malnutrition, disease and poor health.
What did the US officials say?
Speaking at the US Institute of Peace in Washington on Tuesday, Mr Mattis said the US had been watching the conflict “for long enough”.
“We have got to move towards a peace effort here, and we can’t say we are going to do it sometime in the future. We need to be doing this in the next 30 days,” he said.
Mr Mattis added that all sides were being urged to meet UN special envoy Martin Griffiths in Sweden in November and “come to a solution”.
In a separate statement, Mr Pompeo called on the Houthis to end missile and drone strikes on Saudi Arabia and the UAE, and on the coalition to cease air strikes on all populated areas in Yemen.
“It is time to end this conflict, replace conflict with compromise, and allow the Yemeni people to heal through peace and reconstruction,” he added.
The Trump administration has previously backed Mr Griffiths’ mediation efforts and called for a political solution to the conflict in keeping with UN Security Council 2216, which demands that the Houthis withdraw from all areas they have seized and to relinquish their heavy weapons. The Houthis have rejected the resolution.
Why the US ceasefire push is significant
By James Landale, diplomatic correspondent, BBC News
For months the Trump administration has said little about this bloody conflict, leaving its Saudi allies to take the lead. But the remarks by Mr Mattis and Mr Pompeo show the US is now engaging in a way it has not for some time.
Until now both the US and the UK have resisted calling formally for a ceasefire through the UN while it was obvious that neither side was willing to contemplate one. But that seems to have changed. The question, of course, is why?
Diplomats point to the growing pressure from the US Congress to act ahead of the mid-term elections. The US might also be hoping to use the backlash against Saudi Arabia over the murder of Jamal Khashoggi to put pressure on Riyadh to try to end the conflict. Some diplomats have even spoken of a Saudi compromise on Yemen being part of the rehabilitation of Crown Prince Mohammed Bin Salman, the kingdom’s de facto leader.
The big question is how Iran will react. Some diplomats have suggested that Tehran would not be unhappy to step back from Yemen, that its involvement there was always opportunistic rather than strategic, and that it has bigger priorities elsewhere. But it is not clear whether Iran would be willing to help the US when it is re-imposing sanctions on its economy after withdrawing from the Iran nuclear deal.
So the US move is important, but there is still a long way to go before a ceasefire becomes possible, let alone a political process to end the conflict for good.
What has been the reaction?
There was no immediate response from the Saudi-led coalition, the Houthis or Yemen’s government.
But the head of the charity International Rescue Committee, former UK Foreign Secretary David Miliband, said the ceasefire call from Washington was “big news”.
“I hope that this does represent an outbreak of common sense in the American administration, which after all is the key player when it comes to the decisions of the Saudi-led coalition,” he told the BBC.
He also said the UK, China and Russia “should be ashamed at their silence”. “Where are their statements repeating what Mike Pompeo and Jim Mattis have finally said,” he asked.
UK Foreign Office Minister Alistair Burt told a parliamentary committee on Tuesday that the British government was pushing hard for a political solution to the Yemen conflict but that it would not suspend arms sales to Saudi Arabia.