Could shooting off his mouth be shooting himself in the foot?

Throughout his presidential campaign, Mr Donald Trump criticised the Obama administration for being "too soft" on Iran and for allowing it to gain strength in the Middle East.

Mr Trump promised to "rip up" the July 2015 agreement that Iran had signed with the US and five other world powers to limit Teheran's nuclear programme in exchange for lifting international sanctions.

In his first weeks in office, Mr Trump is eager to show he will take a more confrontational approach with Iran, which he called "the No. 1 terrorist state" in an interview.

Teheran provided an opening on Jan 29, when it tested a medium-range ballistic missile.

Iranian officials claimed the launch did not violate a United Nations Security Council resolution that prohibits Iran from testing weapons systems which can carry nuclear warheads.

Iran, which has a history of pushing boundaries with the US, timed its latest missile test to gauge how the new administration would respond.

The administration imposed sanctions on 25 people and entities involved in developing Iran's missile programme or helping the Islamic Revolutionary Guard Corps in supporting groups Washington has designated as terrorist organisations.

Recently, Mr Trump's National Security Adviser Michael Flynn declared: "The Trump administration will no longer tolerate Iran's provocations that threaten our interests."

Hours before, Mr Trump fired off a series of tweets, including one that warned: "Iran is playing with fire - they don't appreciate how 'kind' president Obama was to them. Not me!"

These comments set the framework for a new policy towards Iran. If he is not careful, Mr Trump may risk boxing the US into a position where it has to respond forcefully to any future Iranian missile tests or meddling in the region.

Beyond that danger, the new administration needs Iran in its fight against the Islamic State in Iraq and Syria (ISIS), in both Syria and Iraq, a battle Mr Trump has identified as his highest foreign policy priority.

On Jan 28, he signed an executive order giving the Pentagon and national security officials 30 days to submit a plan for "defeating" ISIS.

But by picking a fight with Iran, Mr Trump could be shooting himself in the foot before he even starts his own battle against ISIS.

Iran's supreme leader, Ayatollah Ali Khamenei, fired back at Mr Trump on Feb 7, declaring sarcastically in a speech: "We actually thank this new President! We thank him, because he made it easier for us to reveal the real face of the United States."

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Of all the regional players, Iran gained the most from America's invasion of Iraq in 2003. Washington ousted Teheran's sworn enemy, Saddam Hussein, from power and helped install a Shi'ite government for the first time in Iraq's modern history.

As US troops got bogged down in fighting an insurgency and containing a civil war, Iran extended its influence over all of Iraq's major Shi'ite factions.

Iran fuelled the Iraqi civil war by arming and training Shi'ite militias targeting American troops and Iraqi Sunnis.

The Iranian regime has several interests in its neighbour: Iraq provides a buffer against Saudi Arabia and other Sunni Arab states that compete with Iran for dominance over the Persian Gulf.

The Trump administration has been signalling that it would side against Iran in Teheran's rivalry with Sunni Arab states, especially Saudi Arabia.

After the 2015 nuclear deal, Saudi leaders were worried Iran would gain the upper hand. Under the deal, Iran re-entered the global financial system, increased its oil exports and accessed billions in frozen assets.

Iran and Saudi Arabia back competing factions in Iraq, Syria, Yemen, Lebanon and Bahrain - and the proxy battles have shaped the Middle East since the American invasion of Iraq.

The Trump administration seems to be wading into this larger competition through Yemen, where Saudi Arabia launched a war in 2015 against Houthi rebels and their allies.

The Houthis, who belong to a sect of Shi'ite Islam called Zaydis, are allies of Iran.

The Saudis have been quick to label the Houthis as Iranian proxies, but it is unclear what support they received from Teheran before the Saudi-led war.

Under Mr Obama, the Pentagon has given billions of dollars in smart bombs and spare parts - as well as intelligence assistance - to help the Saudi air force continue bombing Yemen.

The Trump administration has adopted Saudi Arabia's labelling of the Houthis as Iranian proxies. Ironically, the Yemen conflict is creating more extremism by allowing militants affiliated with ISIS and Al-Qaeda in the Arabian Peninsula to establish new safe havens.

The war in Yemen will not end without some accommodation between Saudi Arabia and Iran. But the Trump administration's rhetoric and adopting of Saudi positions risks inflaming the conflict.

Mr Trump's tough talk against Iran will ultimately hamper his ability to confront ISIS and other jihadists - his No. 1 enemy. - REUTERS

Mohamad Bazzi is a journalism professor at New York University and former Middle East bureau chief at Newsday. He is writing a book on the proxy wars between Saudi Arabia and Iran.