"Given what we know about Trump and his administration, it is very likely that personal financial interests also shape the decisions of the president, his advisors, and some members of his cabinet," Picard said.
Picard stated that the continued support of the United States for the Saudi-led coalition could provoke a broader regional conflict in the Middle East.
"This support also perpetuates the world's worst humanitarian crisis, and increases the likelihood of a broader conflict between the US, its regional allies, and Iran; such a war would be disastrous for the US as well as for the people of Iran and the Arabian Peninsula," Picard said.
In the letter, however, Trump indicated that the United States remained committed to accelerating negotiations to end its military engagements in other regional states such as Afghanistan and Syria.
Yemen has been suffering from a conflict between forces loyal to President Abd Rabbuh Mansur Hadi and the Shiite Houthi movement which escalated after a Saudi-led coalition intervened in 2015 to back the Yemeni government. The conflict has resulted in a massive humanitarian crisis that the United Nations has deemed the worst in the world.