A South Korean military source said movement of road mobile launchers was detected near the North Korean city of Wonsan, according to Yonhap. File Photo by KCNA

SEOUL, Oct. 7 (UPI) -- The United States and South Korea are jointly monitoring North Korea, as Pyongyang appears to have resumed activity at its nuclear site and at other locations.

A South Korean military official who spoke to Yonhap on the condition of anonymity said Seoul has stepped up surveillance of North Korean movements.


The U.S. military has increased the number of U-2 reconnaissance aircraft deployments, and Seoul has sent its RC-800 tactical reconnaissance aircraft, the Geumgang, and the RF-16, the Saemae, on missions to procure intelligence on North Korea's nuclear sites, according to the source.

During a parliamentary audit on Friday South Korea's joint chiefs chairman Gen. Lee Sun-jin said the military surveillance assets of the U.S.-South Korea alliance have been "operating at a heightened level," and military generals have been commanding the control room of the joint forces.

Recent North Korea activity captured in satellite imagery shows work being done at all three tunnels of the Punggye-ri nuclear site, and U.S. and South Korean intelligence have picked up on other activity at the Sohae Satellite Launching Station in Tongchang-ri, North Pyongan Province.

Near the North Korean city of Wonsan, road mobile launchers were being moved around at a military base, according to Yonhap.

There is increased likelihood North Korea could engage in another provocation soon, and as early as Oct. 10, the upcoming anniversary of the founding of the Korean Workers' Party.

According to new analysis from the Center for Strategic and International Studies' Beyond Parallel website, patterns of North Korea provocations show missile and nuclear tests have "clustered increasingly closer to U.S. elections" since Kim Jong Un assumed power.

The average window for a North Korean provocation around all U.S. national elections is about 4 weeks, which makes it plausible Pyongyang's next provocation could take place in a matter of days, according to the study .