10th Special Forces Group-A, embraced the idea. He had a special coin struck with the unit's badge and motto in 1969. Until the 1980s, his unit was the only unit with an active challenge coin tradition. There is another story about an American soldier scheduled to rendezvous with Philippine guerrillas during WWII. As the story goes, he carried a Philippine solid silver coin that was stamped on one side with the unit insignia. The coin was used to verify, to the guerrillas, that the soldier was their valid contact for the mission against the Japanese. The challenge coin tradition has spread to other military units, in all branches of service, and even to non-military organizations as well as the United States Congress, which produces challenge coins for members of Congress to give to constituents. Today, challenge coins are given to members upon joining an organization, as an award to improve morale, and sold to commemorate special occasions or as fundraisers. In the Air Force, military training instructors award an airman's coin to new enlisted personnel upon completion of their United States Air Force Basic Military Training and to new officers upon completion of the Air Force Officer Training School. U.S. presidents Challenge coins issued by presidents' date back to the late 1990s. Separately, the White House Communication Agency (WHCA) has issued challenge coins for foreign heads and military during Presidential visits. In May 2018, controversy arose when WHCA released a coin featuring President Donald Trump and North Korean head Kim Jong-un ahead of peace talks scheduled for June 2018 in Singapore. President Bill Clinton displayed several racks of challenge coins, which had been given to him by U.S. service members, on the credenza behind his Oval Office desks. These coins are currently on display at the Clinton Library. The challenge coins appear in the background of his official portrait, now hanging in the White House. President George W. Bush received a challenge coin from a Marine combat patrol unit during his short but unexpected visit to Al Asad Airbase in Anbar province, Iraq, 3 September 2007. President Barack Obama, in addition to handing challenge coins to U.S. service members, would leave coins on the memorial graves of dead soldiers. President Donald Trump's coin broke with tradition, omitting the presidential seal, the motto "E pluribus unum" and the thirteen arrows representing the thirteen original states. His campaign slogan "Make America Great