US President Donald Trump has defended his decision to pull American troops out of Syria.

“Does the USA want to be the Policeman of the Middle East, getting NOTHING but spending precious lives and trillions of dollars protecting others who, in almost all cases, do not appreciate what we are doing? Do we want to be there forever?” Mr Trump tweeted on Thursday.

Officials announced that Mr Trump was pulling all 2000 US troops out of Syria, as the US President declared victory over the Islamic State. But the move contradicted his own experts’ assessments and sparked surprise and outrage from his party’s members.

Mr Trump said that his decision in Syria should be “no surprise,” adding “I’ve been campaigning on it for years.”

Mr Trump announced on Wednesday that he would begin withdrawing the roughly 2000 US troops from war-torn Syria, although the White House declined to offer a timeline.

Some of Mr Trump’s fellow Republicans fiercely criticised the move, saying they were not briefed ahead of time and that the move strengthened the hand of Russia and Iran, which both support Syrian President Bashar al-Assad.

US officials, speaking on condition of anonymity, have told Reuters that US commanders on the ground are also concerned about the impact of a quick withdrawal.

Meanwhile, Turkish President Recep Tayyip Erdogan and Iranian counterpart Hassan Rouhani vowed to work closer to end the fighting in Syria.

But the two leaders made no comment on Mr Trump’s shock announcement that he was pulling US troops out of the war-ravaged nation.

“There are many steps that Turkey and Iran can take together to stop the fighting in the region and to establish peace,” said Mr Erdogan, without elaborating, at a joint press conference with Mr Rouhani in Ankara.

“Syria’s territorial integrity must be respected by all sides. Both countries are of the same opinion regarding this,” Mr Rouhani said in translated remarks.

The two leaders’ meeting had been arranged before Mr Trump’s announcement about the US pullout, a move already welcomed on Thursday by Russian President Vladimir Putin.

Some Western analysts consider the US presence a key counterweight to Iranian influence in the region.