US Secretary of State Mike Pompeo has begun a visit to the Middle East aimed at ramping up regional efforts to put pressure on Iran and assuaging allies' fears over Washington's plan to withdraw troops from Syria.

Speaking in the Jordanian capital on Tuesday, Pompeo said the United States was "redoubling" its diplomatic and commercial efforts to counter Tehran's "malign influence" in the region.

Any US troop pullout from Syria would not undermine the battle against the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) group, he said at the joint press conference with Jordanian Foreign Minister Ayman Safadi in Amman.

"The most significant threats to the region are Daesh and the Islamic revolution," Pompeo said referring to ISIL and Iran.

A major focus of Pompeo's eight-nation tour is sustaining a regional coalition to counter Iran, branded by Washington as a sponsor of terrorism and the main enemy of US allies Saudi Arabia and Israel.

His appearance in Jordan will be followed by visits to Egypt, Bahrain, Qatar, Saudi Arabia, Oman and Kuwait.

Iran's Foreign Minister Mohammad Javad Zarif swiftly hit back at the latest US broadsides, tweeting that the "pure obsession with Iran is more and more like the behaviour of persistently failing psychotic stalkers".

While ordinarily it might be flattering, @SecPompeo's and @AmbJohnBolton's pure obsession with Iran is more and more like the behavior of persistently failing psychotic stalkers.

In effect, US is substituting a real foreign policy with Iran- obsession and -phobia. — Javad Zarif (@JZarif) January 8, 2019

Troop withdrawal confusion

Pompeo's trip comes just weeks after US President Donald Trump announced that the US would quickly pull its 2,000 soldiers out of Syria, declaring that ISIL had been defeated.

His advisers have since been walking back his timeline, suggesting the conditions for any such withdrawal from northeastern Syria are finishing off ISIL and Turkey assuring the safety of Kurdish troops allied with the US.

Pompeo's trip coincided with a visit to Turkey by US National Security Adviser John Bolton.

The White House aide held talks with Turkish officials in Ankara amid growing tensions over his earlier comments that the US retreat was conditional on the safety of US-backed Kurdish fighters, who are considered terrorists by Turkey.

On Tuesday, Pompeo tweeted that the US's "tactics have changed, not the mission", adding that Washington's campaign to defeat ISIL would continue.

Just landed in Jordan, my first stop on an 8-day Mideast tour. Looking forward to discussing the U.S. withdrawal from #Syria and our continuing #defeatISIS campaign. Our tactics have changed, not the mission! pic.twitter.com/xNh9a6ml2x — Secretary Pompeo (@SecPompeo) January 8, 2019

Al Jazeera's senior political analyst, Marwan Bishara, said the mixed messages appearing to emanate from Trump's administration pointed to continued US "flip-flopping" on its policy in the Middle East.

"There's always this first statement that comes out from Trump that's not necessarily the same as one that comes out later and that's not necessarily one that will endure for a long time," Bishara said.

"Arabs in the region have been receiving mixed messages from Washington."

Pompeo is expected to deliver an address on the US's Middle East policy while in Egypt, whose military ruler-turned-President Abdel Fattah el-Sisi is one of Trump's key partners.

Al Jazeera's Stefanie Dekker, reporting from the Jordanian capital, Amman, said the diplomatic tour is primarily aimed at reassuring Washington's allies with regard to the "Iranian threat" and to "fears about the US troop pullout".

"All the countries he will be visiting will have their own questions to ask," Dekker said.