A U.S. military official said Thursday Iranian cargo ships which may be carrying weapons for Houthi rebels in war-torn Yemen are moving away from that country.
The official, speaking anonymously, calls this a "promising sign."
He said, however, that the Pentagon will continue to watch the ships carefully.
The White House has said it has seen evidence that Iran supplied arms to the Shi'ite Houthis in Yemen. The Pentagon has deployed a number of U.S. warships to Yemeni waters to ensure that key Gulf shipping channels stay open.
Military officials deny the U.S. fleet is there to intercept Iranian ships.
In Yemen, Saudi-led coalition warplanes struck rebel targets Thursday near the southern port of Aden.
The Saudis announced this week that they are officially ending the campaign of airstrikes, but would start up the bombing again if necessary.
A month of airstrikes has killed hundreds of civilians and destroyed homes, but have generally failed to stop the Houthis and return Western-backed President Abd-Rabbu Mansour Hadi to Yemen.
He is currently in exile in Saudi Arabia.
Also Thursday, United Nations Secretary-General Ban Ki-moon nominated Mauritanian diplomat Ismail Ould Cheikh Ahmed as his new special envoy to Yemen.
Cheikh Ahmed, who has been serving as U.N. Ebola chief, would replace Jamal Benomar, who resigned last week after losing support from Gulf countries for his mediation efforts in Yemen.
The appointment becomes official on Monday if no objections are raised by the 15-member Security Council.
Saudi Arabia's ambassador to the United States, Adel al-Jubeir, said Wednesday the bombing campaign has achieved its primary objectives.
"We destroyed the air force; we destroyed their ballistic missiles as far as we know; we destroyed their command and control; we destroyed much, if not most, of their heavy equipment and we made it very difficult for them to move from a strategic perspective," al-Jubeir said.
"So we have degraded their capabilities substantially and thereby eliminated the threat that they posed to the Kingdom of Saudi Arabia and in the process ensured the safety of our borders, our territory and our citizens," he added.
However, Al-Jubeir said there is "no military solution" to the conflict, and that the only way to achieve peace is through U.N.-sponsored peace talks. The Houthis also have expressed a desire to return to the talks.
Last week, the U.N. secretary-general said the U.N.-supported diplomatic process "remains the best way out of a drawn-out war with terrifying implications for regional stability."
The United States supported the bombings, but also welcomed the decision by the Saudi-led coalition to stop the campaign. The White House called for a quick resumption of talks by all Yemeni parties in an inclusive political transition process.
But White House spokesperson Jen Psaki said despite the declared halt to the airstrikes, there is instability in Yemen and the region. Psaki told CNN that "obviously, the job is not done."
Iran welcomed what it called the end to "killing innocent and defenseless civilians" and called the move a "step forward" toward a political resolution.
According to the World Health Organization, 1,080 people have been killed and 4,352 wounded over the past month in Yemen.
Some material for this report comes from AFP and Reuters.