Afghanistan–United States relations began in 1921 after Amanullah Khan had become king of Afghanistan and Warren G. Harding the 29th president of the United States. The first contact between the two nations occurred further back in the 1830s when the first recorded person from the United States explored Afghanistan. The United States began investing some money in landlocked Afghanistan, which ended before the 1978 Saur Revolution. Beginning in 1980, the United States began admitting thousands of Afghan refugees for resettlement, and provided money and weapons to the Mujahideen through Pakistan's Inter-Services Intelligence (ISI).