"Good to see my friend Prince Harry in London to discuss the work of our foundations & offer condolences to victims of the Manchester attack," Obama tweeted.

The Palace tweeted that Prince Harry hosted the 44th president of the U.S., explaining "they discussed support for veterans, mental health, conservation, empowering young people and the work of their respective foundations ... [Barack Obama] also offered his condolences to the victims of the Manchester attack and support for those recovering from injuries."

Obama's relationship with the royals has solidified over the years: In 2011, newlyweds Prince William and Kate Middleton met the Obamas at Buckingham Palace as their first public engagement together. And a few years later, William visited the White House, where he and the then-president discussed illegal wildlife trafficking.