A top Republican lawmaker has urged the Pentagon to begin moving U.S. military dependents — wives and children — out of South Korea, warning that war with nuclear-armed North Korea is "getting close."

The warning by Sen. Lindsey Graham came as the U.S. kicked off a massive joint aerial exercise with South Korea involving 12,000 U.S. personnel and more than 230 aircraft from both countries, including advanced U.S. stealth fighter jets.

"It's crazy to send spouses and children to South Korea, given the provocation of North Korea," Graham, a member of the powerful Senate Armed Services Committee, said on CBS's "Face the Nation." "So I want them to stop sending dependents. And I think it's now time to start moving American dependents out of South Korea."