US President Donald Trump speaks to workers during a visit to the Cameron LNG (Liquid Natural Gas) Export Facility in Hackberry, Louisiana, US, May 14, 2019. Photo: REUTERS/Leah Millis.

US President Donald Trump threatened Iran in a tweet on Sunday, raising concerns about a potential US-Iran conflict at a time when tensions between Washington and Tehran have risen.

“If Iran wants to fight, that will be the official end of Iran. Never threaten the United States again,” Trump said in a tweet.

Trump has tightened economic sanctions against Iran, and his administration says it has built up the US military presence in the region. It accuses Iran of threats to US troops and interests.

Tehran has described US moves as “psychological warfare” and a “political game.”