U.S. analysts say North Korea appears to have restored normal operations at a long-range rocket launch site it partially dismantled last year as part of disarmament steps.

Analysts say North Korea is trying to convey displeasure over the breakdown of a summit between leader Kim Jong Un and President Donald Trump over what the Americans said were Kim's excessive demands for sanctions relief.

North Korea-focused website 38 North says commercial satellite images from March 6 indicate that the launch site appears to have returned to "normal operational status" after rapid construction there.

The Washington-based Center for Strategic and International Studies has published similar findings and says the North's actions amount to a "snapback" from the moderate dismantlement it undertook following the first Trump-Kim summit last June.