The new head of the UN observer mission, Retired Danish general Michael Lollesgaard, arrived in Yemen on Tuesday to replace his predecessor, retired Dutch general Patrick Cammaert.
Cammaert was appointed to the position in December following talks in Sweden between the legitimate government and Iran-backed Houthi militias that led to an agreement on a ceasefire in the port city of Hodeidah.
The UN observer mission was formed to oversee the implementation of the truce that has been hampered by Houthi intransigence.
Lollesgaard made no comments upon his arrival in Sanaa, an AFP correspondent said, and it was not clear when exactly he would begin his mission in Hodeidah.
Diplomats say relations have been strained between Cammaert and the Houthis.
The Houthis have accused him of running his own agenda, a claim disputed by the United Nations which said his only mission was to improve the lives of the embattled Yemeni people.
On January 17, his convoy came under fire in Hodeidah but he and his team escaped unhurt.
Lollesgaard, born in 1960, commanded the UN peacekeeping force in Mali (MINUSMA) from 2015 to 2016, and he then became Denmark's military representative to NATO and the European Union in 2017.
He was also military adviser to Denmark's UN mission in New York and served in peace support operations in Iraq and Bosnia
His new appointment was endorsed at the end of January by the UN Security Council.
Meanwhile, in Amman, the warring Yemeni parties began a new round of UN-brokered talks on a troubled prisoner swap deal that was agreed to during the Sweden talks.
At the end of January, the Houthis released a captured Saudi soldier while Riyadh set free seven Houthi prisoners but they are the only detainees exchanged under the deal so far.
UN envoy Martin Griffiths said he hoped the two sides would be more successful this time as he opened three days of talks in Amman.
"The aim of this event is to finalize... the lists of prisoners and detainees to be released and exchanged," he said.
"Success in this regard is not only of huge importance for those who will be released and return to their families but also to the broader political process in which we are engaged."
A senior official of the International Committee of the Red Cross, which will oversee the deal's implementation, said on Monday that it was "hanging in the balance," with trust among the parties "insufficient".
Each side has presented a list of up to 8,000 detainees to be freed, but many names cannot be accounted for, said the ICRC's director of operations, Dominik Stillhart, adding that the prisoner swap realistically would involve a significantly lower number.
