An airstrike carried out by the Saudi-led coalition in Saada, Yemen's northern province, hit a bus carrying children from a summer camp on August 9, killing 51 people, including 40 minors.
The CNN broadcaster has learned that US Defense Secretary James Mattis and Gen. Joseph Votel, head of US military operations in the Middle East, were concerned that Washington was supporting a Saudi-led campaign of airstrikes that killed multiple civilians.
Pentagon spokeswoman Lt. Cmdr. Rebecca Rebarich told Sputnik on August 16 that the US Department of Defense was working with Congress on the issue of US military involvement in attacks in Yemen.
Yemen has been engulfed in an armed conflict between the government headed by President Abd Rabbuh Mansur Hadi and Houthi rebels since 2015.
The Saudi-led coalition of mostly Persian Gulf nations has been carrying out airstrikes against the Houthis at Hadi's request since March 2015.