North Korea is jamming GPS devices in South Korea, affecting hundreds of passenger jets, commuters, Uber drivers and commercial fishing boats while raising alarm bells in the Pentagon, multiple defense officials confirmed to Fox News Wednesday.

The U.S. has sent roughly 30,000 troops to protect the South Korean border in a war that began in 1950. It's technically ongoing, as no peace treaty was ever signed. The signal-jamming would not affect U.S. military members who use encrypted GPS, according to officials.

South Korean officials said the attempt to jam GPS signals, which began Thursday, did not cause any major disruptions of South Korean military, aviation and sea transport and telecommunication systems. However, more than 130 fishing boats reported problems with their navigation systems and some were forced to return to their ports, the Ministry of Oceans and Fisheries said.

South Korea's Defense Ministry called the jamming attempt a provocation that threatened public safety and military operations in the South. A ministry statement warned North Korea to immediately stop the jamming efforts or face unspecified consequences.

South Korea has blamed North Korea for several previous jamming attempts. The recent round of signal-jamming is the first since 2012, according to South Korea's Science Ministry. North Korean state media had no immediate comment.

Tensions are running high on the divided Korean Peninsula. The U.N. Security Council has imposed stiffer international sanctions on North Korea, and since the start last month of annual South Korea-U.S. military drills, the North has threatened nuclear strikes on Seoul and Washington and warned it will test a nuclear warhead and ballistic missiles capable of carrying it.

Fox News' Lucas Tomlinson and The Associated Press contributed to this report.