CNN: Trump on immigration: 'They have to go'

(CNN) Donald Trump says he would undo all of President Barack Obama's executive moves to forestall deportations of undocumented immigrants if he's elected president.

"They have to go," the real estate mogul who is leading Republican primary polls nationally and in the key early-voting states of Iowa and New Hampshire, said in an interview aired Sunday on NBC's "Meet the Press."

In the wide-ranging interview, Trump also declined to rule out shutting down the federal government over Planned Parenthood.

He called for the United States to seize oil in Iraq -- particularly the oilfields controlled by ISIS. And he warned of a "nuclear holocaust" if the Iran deal is implemented.

But Trump's top campaign issue so far has been his focus on immigration. He told NBC Obama's moves that allow undocumented immigrants who were brought into the United States as children to stay, as well as actions that allow the undocumented parents of U.S. citizen children to avoid deportation.

Trump said he would deport families "together." They'd be required to leave the United States and only then could some come back under an expedited process, he said, because "we either have a country or we don't have a country."

More: www.cnn.com