The news comes as Sudan considers withdrawing from participation in the Saudi intervention, which has now been in progress for over three years.
A team of around a dozen Green Berets were sent to Saudi Arabia's border with Yemen in December 2017 after Saudi Arabia's Crown Prince Mohammed bin Salman reportedly asked the USA to help the country locate and destroy Houthi ballistic missile launch sites, according to United States officials and European diplomats.
But even the previously disclosed US assistance has come under congressional scrutiny amid a mounting civilian death toll from the Saudi-led coalition's bombing campaign in Yemen, as well as what some lawmakers call an illegal deployment of USA military forces.
It claimed the American soldiers are also working with surveillance aircraft to track Houthi weapons and their launch sites.
Local military analysts said that the Houthis are facing a real difficulty in recruiting new fighters particularly in the port city Hodeidah, as most of the young fighters preferred to join with the forces loyal to the Saudi-backed Yemeni government.
The US military is more deeply involved in the Saudi War in Yemen than officials ever admitted.
Qatar's state-linked National Human Rights Committee condemned what it said was the April 21 detention of Mohsen Saleh Saadoun Al-Karbi by a Saudi-led coalition that is fighting in Yemen against the Houthi movement that controls the capital.
"We are authorized to help the Saudis defend their border", Gen. Joseph Votel, head of U.S. Central Command, told the Senate Armed Services Committee on March 13.
The Pentagon's "limited non-combat support, such as intelligence sharing, focuses on assisting our partners in securing their borders from cross-border attacks from the Houthis", military spokesman Major Adrian Rankine-Galloway said. Sources also told the newspaper that the United States troops are training their Saudi counterparts to secure the border with Yemen. They were launched from the northern Yemeni province of Omran. Clearly, it also involved physical USA troops on the border. Yet there is no evidence that the Houthis directly threaten the United States; they are a group with no operations outside Yemen and have not been classified by the US government as a terrorist group.
In the meantime, Saudi war planes conducted a string of airstrikes against the Yemeni governorates of Saada, Al Hudaydah and Hajjah held by the Houthi rebels.
Members of the Sudanese parliament urged President Omar al-Bashir to withdraw troops from Yemen on Sunday, arguing that the extended deployment is unconstitutional and Sudan "should not interfere in the affairs of other countries".
It reported dozens of casualties.