Three years after the Sept. 11, 2001, terrorist attacks on the United States, the war on terrorism, launched in the aftermath of the tragedy, is still raging on and has become a central theme in this year's US presidential elections.

The war on terrorism "will certainly become an important factor " in the Nov. 2 presidential elections and "it will probably become the single most important issue," Ted Galen Carpenter, vice president for Defense and Foreign Policy Studies at the Washington-based thinktank Cato Institute, told Xinhua in an interview.

Both President George W. Bush and his rival, Democratic presidential candidate John Kerry, have to play the anti-terror card since terrorism is, as Carpenter put it, "the concerns of theAmerican people."

Carpenter was echoed by Thomas Sanderson, deputy director of the Transnational Threats Initiative at the Center for Strategic and International Studies in Washington.

The war on terror is one of the top issues along with Iraq and the economy, Sanderson told Xinhua.

Sanderson said this was unlike the previous US presidential elections in which the economy had always been the top priority for both the Republicans and the Democrats.

President Bush launched the war on terrorism shortly after the Sept. 11 attacks which killed nearly 3,000 people and destroyed the World Trade Center twin towers, the heaviest terrorist attacks the country has ever suffered.

Since then, Bush has portrayed himself as a strong, decisive leader in the war on terrorism, unafraid to make tough decisions in a dangerous world, and consequently scored approval ratings as high as 92 percent after the attacks.

As the Sept. 11 anniversary is approaching, the Republicans held their national convention from Aug. 31 to Sept. 2 at New York's Madison Square Garden, just four miles away from Ground Zero.

The Republicans' move, widely regarded as a painstaking effort to remind the Americans of the terrorist attacks as well as Bush's strong leadership, has aroused accusation from the Democrats that the Republicans are exploiting the tragedy.

Bush's approval ratings, however, have been falling sharply due to the Iraq war he started in March last year to topple Saddam Hussein's regime without the authorization of the UN Security Council.

"One lesson from the Sept. 11 attacks is that we can not use the war on terrorism as a label or pretext to accomplish other goals, as we did in Iraq. That was a mistake. That will cause problems in our overall anti-terror strategy," Carpenter said.

Moreover, the Bush administration has been accused of exploiting the war on terrorism to seek military and political influence in the oil-rich Central Asia.

The anti-terror war has gains, "but by launching the Iraq (war) and occupying that country, our policies have probably created even more recruits for the al-Qaida and its allies," Carpenter said.

Sharing a similar view, Sanderson said the war on terrorism "is not going on as well as it could have been if we had focused on Afghanistan and not on Iraq."

More than one year has passed since Bush declared an end to major combat in Iraq, the United States has not found any weapons of mass destruction in Iraq, a major excuse for Bush to go to war with the country.

In an interview with NBC's "Today" show on Aug. 30, Bush, portraying himself as a strong and decisive leader, said he did not think the war on terrorism could ever be won, but he reversed the comment the next day vowing that the war on terror would be won.

"I do not think you can win it. But I think you can create conditions so that those who use terror as a tool are less acceptable in parts of the world," Bush told NBC in the interview.

White House officials have scrambled to explain that Bush was merely reiterating his belief that the unconventional "war on terror" would not end with a peace treaty. Democrats have pounced on Bush's remarks as a sign of defeatism.

Carpenter said Bush was right when he said it was impossible to win the anti-terror war in the way of a conventional war where you capture the enemy's capital city or force the surrender of its army, "but we have to be careful of (what) we do."

"We risk turning the entire Islamic world against us. If we do that, the terrorist strike we have seen at this point will be mild compared with the terrorist strike we are bent on confronting," Carpenter warned.