The U2 frontman also warned President Trump's budget cuts will put progress at risk, meaning "needless infections and lives lost."
Since George W. Bush's presidency, Bono and the former head of state have developed somewhat of an unlikely friendship over their shared mission to fight the global HIV/AIDS epidemic and save the lives in Africa.
On Friday, the U2 frontman shared a photo with Bush taken at the former president's ranch in Crawford, Texas, applauding his righteous work and warning against the current president's proposed budget. In turn, Bush returned the praise with some kind words of his own.
"More than 11 million people are alive today thanks to this man's creation of PEPFAR, the U.S. AIDS program that has been saving lives and preventing new HIV infections for over 10 years, with strong support from political leaders right, left, and center. That progress is all at risk now with President Trump's budget cuts, which will mean needless infections and lives lost," Bono wrote on the Instagram page of his ONE campaign non-profit, which works to fight extreme poverty and preventable disease, particularly in Africa.