North Korea's top envoy visits Iran

North Korean Foreign Minister Ri Yong-ho held talks with his Iranian counterpart Mohammad Javad Zarif Tuesday as Tehran rejoined Pyongyang in being forced to operate under American sanctions.

The two leading diplomats agreed to a "further expansion of ties," according to Iran's Islamic Republic News Agency.

Without providing specific details, the state-run media outlet also stated that they "discussed the latest regional and international developments as well as issues of mutual interest".

It is understood to be the first time a senior North Korean official has visited Iran since leader Kim Jong-un held an unprecedented summit with U.S. President Donald Trump in June.

Ri was critical of the U.S. last weekend at the ASEAN Regional Forum, where he accused Washington of being too focused on maintaining sanctions when Pyongyang has been taking peaceful measures agreed during the Kim-Trump meeting.

Washington has made clear that North Korea can enjoy prosperity through global investment -- if it denuclearizes.

While Trump has also offered dialogue to Tehran, the American leader posted on Twitter Tuesday that the latest punitive action against Iran forms "the most biting sanctions ever imposed".

He additionally warned that "anyone doing business with Iran will NOT be doing business with the United States".