CIA Director Mike Pompeo is in South Korea holding talks with top officials and military leaders, as tensions remain elevated on the Korean Peninsula.

South Korea's Yonhap news agency reported he arrived over the weekend and already held meetings with his counterpart in South Korea's National Intelligence Service. It also cited sources as saying the CIA chief met with other officials at the presidential palace in Seoul.

The unannounced visit to South Korea comes as tensions remain high in the region after a failed ballistic test early Saturday by the regime led by Kim Jong Un. It comes as a carrier strike group led by the USS Carl Vinson holds drills off the peninsula with South Korea.

There are concerns the 33-year-old leader may conduct the country's sixth nuclear test at any time.

North Korea threatened to "speed up" the pace of its nuclear program, according to a Foreign Ministry spokesman quoted Monday by the official KCNA news agency. The North added that it "will continue to bolster its military capabilities for self-defense and preemptive nuclear attack with the nuclear force as a pivot."

Pompeo also was reported to have consultations with Seoul over the THAAD missile defense system, which is designed to protect against missile and nuclear threats from Pyongyang.

Last week, President Donald Trump threatened to "terminate" the free trade deal with South Korea unless it paid for the THAAD system. But the administration has since reassured Seoul that the U.S. will pay the costs of the deployment.

On Saturday, Pompeo flew to Osan Air Base south of Seoul, the South Korean paper Kookmin Ilbo reported. The next day he held a dinner meeting with the acting U.S. ambassador to South Korea, Marc Knapper.

The Seoul paper said Pompeo's visit is a review of the "security crisis on the Korean Peninsula" as well as a fact-finding trip to learn about the Korean presidential election and possible North Korean policy change. The South Korean presidential election is scheduled for May 9.

The CIA director is expected to remain in South Korea through Tuesday, the newspaper said.