Robert O’Brien, who served as national security adviser in the Trump administration, has reiterated the need for allies to increase their spending on defense, including their share of the costs for the upkeep of U.S. troops. 

O’Brien made the call Sunday in an interview with CBS, saying the American taxpayers can’t deter China alone and the U.S. needs help from its allies.

When the host mentioned that allies like South Korea and Japan are already helping to pay for some of the costs, O’Brien said they are paying “some of the costs, but not enough” and so the American taxpayers took a "tremendous burden."

He claimed that South Korea, Japan and Australia, as well as European countries, have raised their defense spending very significantly because of former President Donald Trump, which makes the U.S. stronger against China. 

There is speculation that O’Brien, who served as national security adviser through the end of Trump’s term, will be reappointed as national security advisor or named secretary of state or defense secretary if Trump is reelected in November.