US Election Trump says Clinton policy on Syria will lead to World War III Trump said defeating Islamic State is a higher priority than persuading Syrian President Bashar al-Assad to step down.

Republican presidential nominee Donald Trump speaks during a rally at the Delaware County Fair in Delaware, Ohio, on October 20, 2016
(AFP)

U.S. Republican presidential nominee Donald Trump said on Tuesday that Democrat Hillary Clinton's plan for Syria would "lead to World War Three," because of the potential for conflict with military forces from nuclear-armed Russia.

In an interview focused largely on foreign policy, Trump said defeating Islamic State is a higher priority than persuading Syrian President Bashar al-Assad to step down, playing down a long-held goal of U.S. policy.

Trump questioned how Clinton would negotiate with Russian President Vladimir Putin after demonizing him; blamed President Barack Obama for a downturn in U.S. relations with the Philippines under its new president, Rodrigo Duterte; bemoaned a lack of Republican unity behind his candidacy, and said he would easily win the election if the party leaders would support him.

"If we had party unity, we couldn't lose this election to Hillary Clinton," he said.

On Syria's civil war, Trump said Clinton could drag the United States into a world war with a more aggressive posture toward resolving the conflict.

Clinton has called for the establishment of a no-fly zone and "safe zones" on the ground to protect non-combatants. Some analysts fear that protecting those zones could bring the United States into direct conflict with Russian fighter jets.

"What we should do is focus on ISIS. We should not be focusing on Syria," said Trump as he dined on fried eggs and sausage at his Trump National Doral golf resort. "You're going to end up in World War Three over Syria if we listen to Hillary Clinton.

"You're not fighting Syria any more, you're fighting Syria, Russia and Iran, all right? Russia is a nuclear country, but a country where the nukes work as opposed to other countries that talk," he said.

Clinton's campaign dismissed the criticism, noting that both Republican and Democratic national security experts have denounced Trump as unfit to be commander-in-chief.

"Once again, he is parroting Putin's talking points and playing to Americans' fears, all while refusing to lay out any plans of his own for defeating ISIS or alleviating humanitarian suffering in Syria," Clinton spokesman Jesse Lehrich said in a statement.

Trump said Assad is much stronger now than he was three years ago and said getting Assad to leave power was less important than defeating Islamic State.

"Assad is secondary, to me, to ISIS," he said.