North Korea started “aggressively” jamming the BBC’s new Korean language service on the same day it began, according to a report.

The service began broadcasting Tuesday to provide “news, sport, business and culture” to audiences “in the Korean peninsula and Korean speakers around the world” online and on radio, the British broadcaster said when announcing the launch.

“A key focus of the service is North Korea, where government censorship restricts access to independent news,” it added.

Listening to foreign radio stations is illegal in North Korea. The BBC’s shortwave channels were “aggressively targeted” by radio jamming on the first evening of broadcasts, according to 38 North, a website run by the U.S.-Korea Institute at the Johns Hopkins University School of Advanced International Studies in Washington.

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It said during radio jamming, a loud noise is transmitted over stations so that listeners can’t hear the content. South Korean officials have previously said that North Korea used radio waves to jam GPS systems, affecting planes and ships.

The BBC broadcasts are carried on shortwave frequencies from Taiwan and Uzbekistan, and on medium wave from Mongolia, 38 North reported. It said it wasn’t possible to determine if the medium wave frequency was also targeted by jamming.

North Korean defectors have admitted to listening to foreign broadcasts, with some even saying they helped them decide to leave their reclusive homeland, according to 38 North.

There is “little doubt of who the real target” of the BBC’s broadcasts is, the website added.

The BBC didn’t immediately respond to a request for comment.

The development comes amid a war of words between President Trump and North Korean leader Kim Jong Un.

South Korean lawmaker Lee Cheol-uo said North Korea was bolstering its defenses by moving aircraft to its east coast after U.S. warplanes flew east of the area in a show of force, Reuters reported Tuesday. Lee said the U.S. seemed to have disclosed the flight route intentionally because North Korea appeared to be unaware.

Reuters said a U.S. official told it that satellite images detected a small number of North Korean military aircraft moving to the east coast, but that did not change the assessment of North Korea's military stance.

North Korea's foreign minister said Monday that Trump has declared war on the reclusive nation and that Pyongyang has the right to shoot down U.S. military aircraft, “even when they are not yet inside the airspace border of our country."

Pyongyang conducted its sixth and most powerful nuclear test to date earlier this month and was hit with tough new U.N. sanctions. North Korea responded by launching a ballistic missile over Japan. The U.S. military then flew bombers and fighter jets over the Korean Peninsula and near Japan.