PHOENIX (Reuters) - U.S. President Donald Trump expressed cautious optimism on Tuesday about a possible improvement in relations with North Korea after months of mounting tension over its weapons programs.

"I respect the fact that he is starting to respect us," Trump said of North Korean leader Kim Jong Un.

"And maybe - probably not, but maybe - something positive can come about," he said at a campaign rally in Phoenix, Arizona.

(Reporting by Steve Holland; Writing by Eric Walsh; Editing by Paul Tait)