SINGAPORE (AP) — As he prepares for a momentous meeting with North Korean leader Kim Jong Un, President Donald Trump has plenty of other things on his mind, too.

The president piled on more tweets Monday in his escalating trade war with Canada. And Trump sent out a top official to bash news reporting suggesting his summit preparations could have been hindered by the lack of a top science adviser.

The side issues could serve as a potential distraction from the summit that Trump has hoped to make a legacy-defining moment for his presidency.

While aboard Air Force One en route to the summit, Trump tweeted out a plug for South Carolina Gov. Henry McMaster ahead of Tuesday's South Carolina primary.