Assad told Paris Match no one could predict when the war with insurgents seeking to oust him would end but said enemies had failed to win over the population, allowing the military to advance.
In extracts published on Wednesday, Assad also said U.S.-led air strikes in Syria since September were an "illegal intervention" that had made no difference in the fight against ISIS militants who are fighting government forces.
"The Syrian army cannot be everywhere at once. Where it is not present, terrorists take the opportunity to cross borders and infiltrate in one area or another," said in the French language magazine in comments translated by Reuters.
"It is not about a war between two armies, where one occupies a territory and the other another one. It is another type of war. We are dealing with terrorist groups that infiltrate a town or village. So this war will be long and difficult.
Assad said the army was progressing in many regions. Asked whether he saw his departure as the solution, he said:"The state is like a ship: the captain does not escape in the storm. He does not quit the deck. If passengers need to leave, then he is the last to go."
He disputed a United Nations estimate claimed that the conflict had killed nearly 200,000 people since 2011, saying figures in the media were exaggerated.
He dismissed the idea Syria's military had allowed ISIS to flourish earlier in the war to wipe out other insurgents and suggested the United States had helped create it."In reality, Islamic State was created in Iraq in 2006. It was the United States which occupied Iraq, not Syria," he said, Adding the group's leader was jailed in a U.S.-run prison there.
"So who created Islamic State? Syria or the United States?"He said Syrian forces had not used chemical weapons because they had more efficient arms to fight "terrorists."
This week Syria's vice foreign minister warns that terror groups are using chemical weapons in iraq and Syria.Mekdad said Monday that terror groups ``have used chlorine gas in several of the regions of Syria and Iraq."
One day later as Sunday Mirror reports “a British ISIS fanatics said the group have built a dirty bomb and boast of the damage it could inflict on London.
The terrorists are said to have made a device using radioactive uranium stolen from Iraq’s Mosul University after seizing control of the city last June.
On october, After reports of ISIS used Chemical Agent against Kurdish fighters in kobane, Iraqi officials confirmed ISIS militants used chlorine gas during fighting with Iraqi security forces and Shiite militiamen in the north of Baghdad.