By Mariam Karouny and Dominic Evans
BEIRUT (Reuters) - President Bashar al-Assad accused the West on Wednesday of supporting al Qaeda militants in Syria's civil war and warned they would turn against their backers and strike "in the heart of Europe and the United States".
Assad also launched his strongest criticism yet of neighboring Jordan for allowing thousands of fighters to cross the border to join a conflict he insisted his forces would win and save Syria from destruction.
"We have no choice but victory. If we don't win, Syria will be finished and I don't think this is a choice for any citizen in Syria," the defiant president said in a television interview.
Assad's forces have been fighting back across the country against rebels who have taken control of much of rural Syria and seized a provincial capital in March for the first time in two years of fighting.
The conflict started with mainly peaceful demonstrations but descended into a civil war in which the United Nations says at least 70,000 people have been killed. Islamist militants have emerged as the most potent of the anti-Assad rebels.
Drawing parallels with Western support for anti-Soviet fighters in Afghanistan in the 1980s, some of whom later formed the al Qaeda organization which attacked the United States in September 2011, Assad said Washington and Europe would regret supporting rebels in Syria.
"The West paid heavily for funding al Qaeda in its early stages in Afghanistan. Today it is supporting it in Syria, Libya and other places, and will pay a heavy price later in the heart of Europe and the United States," he told al-Ikhbariya channel.
"The truth is, what is happening is that we are mainly facing extremist forces," Assad added.
He was speaking a week after Syria's rebel al-Nusra Front, one of the most effective rebel forces battling his troops, formally pledged allegiance to al Qaeda leader Ayman al-Zawahri.
The United States has designated the Nusra Front a terrorist organization and has sought to bolster rival rebel forces to counter the influence of the Islamists, training fighters in neighboring Jordan and allowing arms shipments to them.
In some of his toughest comments against Jordan, Assad said Syria's southern neighbor had allowed thousands of fighters with military gear to cross into Syria to join the fight, and warned that the conflict could spread to Jordanian territory.
"The fire will not stop at our border and everybody knows that Jordan is exposed as Syria is," he said.
He said Syria had sent a security envoy to Amman in recent weeks to inquire about the fighters and reports of rebel training camps but he was met with "complete denial" of any Jordanian role in either issue.
The United States will send 200 troops to Jordan in the coming weeks to help the kingdom boost its defenses in the face of a "deteriorating situation" in Syria, Jordanian Minister of State for Information Mohammad al-Momani told Reuters.
Rebels say U.S. officers in Jordan have been training groups of anti-Assad fighters from Damascus and the southern province of Deraa - where fighting has intensified in recent weeks and rebels have made gains.
"It's not possible to believe that thousands enter Syria with their gear (from Jordan) when Jordan is able to stop or arrest a single person carrying a simple weapon for resistance in Palestine," Assad said.
(Reporting by Dominic Evans and Mariam Karouny; Editing by Jon Hemming)