Yemen's Huthi rebels warned on Saturday they could launch attacks against the capitals of Saudi Arabia and the United Arab Emirates, who lead a military coalition against them.
The threat came as the United Nations was trying to salvage a truce deal in Yemen, seen as crucial to diplomatic efforts to end the country's four-year war.
"We have aerial photographs and coordinates of dozens of headquarters, facilities and military bases of the enemy," rebel military spokesman Yahya Saree said in comments carried by the rebels' Al-Masirah channel.
"The legitimate targets of our forces extend to the capital of Saudi Arabia and to the emirate of Abu Dhabi," capital of the UAE, he said.
"We have manufactured advanced generations of attack aircraft, and new systems will soon be functional."
The Iran-linked Huthi rebels have targeted Saudi border towns and Riyadh with ballistic missiles and also claimed drone attacks on the airports of Abu Dhabi and Dubai during the course of the conflict
Saudi Arabia has said the missiles were all intercepted by its air force, with one civilian reported killed by falling shrapnel, while the UAE has denied the alleged drone attacks.
Saudi Arabia and its military allies joined the Yemeni government's war against the Iran-linked Huthis in March 2015, triggering what the UN calls the world's worst humanitarian crisis.
Some 10 million Yemenis face mass starvation, according to the UN.
Both sides to the conflict stand accused of acts that could amount to war crimes.
The World Health Organization estimates nearly 10,000 people have been killed in Yemen since March 2015, when Saudi Arabia and its allies joined the government's war against the Huthis.
Other rights groups estimate the toll could be much higher.
On Wednesday the UN Security Council met to discuss the stalled truce deal that had been agreed in Sweden in December between the Saudi-backed Yemeni government and the Huthis.
The deal -- which called for a ceasefire, rebel pullback and mutual redeployment from Hodeida, Yemen's lifeline Red Sea port controlled by the Huthis -- offered the best hope in years of moving toward an end to the conflict.
While the fighting in Hodeida has eased, redeployment efforts have stalled in recent weeks.
UN envoy Martin Griffiths told the Security Council on Wednesday he was still working to make the redeployment a "reality".