More than half of top U.S. foreign policy experts oppose President George W. Bush's troop increase as a strategy for stabilizing Baghdad, saying the plan has harmed U.S. national security, according to a new survey.

As Congress and the White House await the September release of a key progress report on Iraq, 53 percent of the experts polled by Foreign Policy magazine and the Center for American Progress said they now oppose Bush's troop build-up.

That is a 22 percentage point jump since the strategy was announced early this year.

The survey of 108 experts, including Republicans and Democrats, showed opposition to the so-called "surge" across the political spectrum, with about two-thirds of conservatives saying it has been ineffective or made things worse in Iraq.

Foreign Policy, published by the Carnegie Endowment for International Peace, said the experts polled on May 23 to June 26 included former government officials in senior positions including secretary of state, White House national security adviser and top military commanders.

The findings were published in the form of a Terrorism Index in the magazine's September/October issue, to be released on Monday. The magazine published similar indices in July 2006 and in February.

Bush has deployed 30,000 additional U.S. forces in and around Baghdad to quell sectarian violence in a bid to foster political reconciliation between Iraqi's Sunni, Shi'ite and Kurdish communities.

The strategy was announced early in the year but U.S. forces did not reach their intended strength in Baghdad until mid-June.

U.S. Ambassador to Iraq Ryan Crocker and the top U.S. commander in Iraq, Gen. David Petraeus, are due next month to provide Congress with a progress report that could prove vital in determining how long U.S. troops stay.

Democrats and some Republicans in Congress say it is time to begin bringing troops home.

Foreign Policy said seven of 10 experts supported the redeployment of U.S. forces from Iraq. Experts have increasingly cited the war as the root cause of what they believe to be U.S. failure to win in its war on terrorism.

Ninety-one percent of those polled said the world has grown more dangerous for Americans and the United States, up 10 percent from February.

More than 80 percent of the experts said they expected another September 11-scale attack on the United States over the next decade, despite what they described as significant improvements among U.S. security, law enforcement and intelligence agencies.

A decade from now, the Middle East still will be reeling from the ill-effects of the Iraq war, particularly heightened Sunni-Shi'ite tensions in the region, 58 percent said.

Thirty-five percent believed Arab dictators will have been discouraged from pursuing political reforms as a result.

Only 3 percent believed the United States will achieve its goal of rebuilding Iraq into a beacon of democracy within the next 10 years.