CAIRO (AP) ― It has been a week of stunning advances by Islamic militants across a belt from Iraq to Pakistan. In Iraq, jihadi fighters rampaged through the country’s second-largest city and swept farther south in their drive to establish an extremist enclave stretching into Syria. Pakistan’s largest airport was paralyzed and rocked by explosions as gunmen stormed it in a dramatic show of strength.

More than a decade after the U.S. launched its “war on terrorism,” Islamic militant groups are bolder than ever, exploiting the erosion or collapse of central government control in a string of nations ― Syria, Iraq and Pakistan ― that are more strategically vital than the relatively failed states where al-Qaida set up its bases in the past: Somalia, Yemen and 1990s Afghanistan.

Most galling to Washington, the crumbling state power has come in countries that the United States has spent billions of dollars to try to strengthen over the past 13 years.

Policy failings by those governments have contributed to giving militants an opening.

Iraq’s prime minister, Nouri al-Maliki, has alienated the country’s Sunni community, which feels sidelined by his Shiite-led government. That has pushed some Sunnis into supporting the militants and undermined the military, which includes many Sunnis.

Notably, the military and police fell apart, abandoning their posts and arsenals of weapons, when Islamic extremist gunmen overran the city of Mosul earlier this week, then swept south into other Sunni-dominated areas Wednesday.

For years, Pakistan has supported militant groups to promote its interests in Afghanistan and against its bitter rival, neighboring India. Now it faces a bloody insurgency by the Pakistani Taliban, an offshoot of the Afghan Taliban that has vowed to topple a government it accuses of being a tool of the Americans.

Islamabad’s authority has always been tenuous in Pakistan’s rugged, tribal-dominated and underdeveloped northwest, near the Afghan border ― and for years that was where militant groups, from al-Qaida to the Taliban, operated. Now, the Pakistani Taliban have expanded to develop a strong presence in the country’s largest city, Karachi, where the airport attack took place and where police are gunned down almost daily.

The Afghan Taliban won a diplomatic victory of its own when the U.S. freed five Taliban detainees last month in a swap for the release of the only remaining U.S. prisoner of war in Afghanistan, Bowe Bergdahl.

U.S. policies have shrunk its options in all these regions. American forces left Iraq more than two years ago without winning agreement on a longer presence from Maliki’s government, ending Washington’s hand in security and virtually robbing it of influence over al-Maliki. Combat troops are on their way out of Afghanistan by the end of the year, which could have a similar effect as the Afghan government takes the lead in fighting the Taliban insurgency.

In Syria, the Obama administration has resisted calls to more strongly arm and finance rebels fighting against President Bashar Assad, in part due to fears of taking on the burden of another war in the Mideast and inadvertently aiding Islamic radicals rather than moderate forces. As a result, better-armed and better-funded extremists have risen to prominence anyway.

“A common theme is the inability of the international community ... to help local actors, local leadership to create more viable institutionally based societies, especially on the security side,” said Salman Shaikh, director of the Brookings Doha Center in Qatar.

As a result, “weak and fragile states” have been unable to create “viable political systems of government, a political culture which is able to manage diversity and pluralism, and a security environment which is there to ... protect rather than to intimidate and impose order,” he said.

Nothing illustrates the potential for Islamic militants to rearrange the region’s map more than the rise of the Islamic State of Iraq and the Levant, the al-Qaida breakaway group that this week took over much of Mosul and then swept into the Iraqi city of Tikrit, farther south.