On his first full day as secretary of state, Marco Rubio is meeting with his counterparts from a group of countries known as the Quad: the United States plus India, Japan and Australia, representing nearly 2 billion people and more than a third of global GDP.

The United States, Australia, India and Japan recommitted to working together on Tuesday, after the first meeting of the China-focused "Quad" grouping's top diplomats since President Donald Trump returned to the White House.