ISTANBUL — When Washington sought to rally world and regional partners last week for an assault on the jihadis of the Islamic State, one crucial ally was notably reluctant: Turkey.

Turkey, a NATO member with the alliance’s second largest army, is seen by Washington as key to combating IS, which Sunni militant group that has taken over swathes of Iraq and Syria.

But visits to Ankara over the past week by US Defense Secretary Chuck Hagel and Secretary of State John Kerry yielded little, with Turkish leaders publicly refusing to play any military role against IS and forbidding the US to use Turkish soil for strikes against the group.

A combination of fear for its own homeland security – and for that of 49 of its citizens currently held hostage by IS – as well as deep differences of opinion with Washington over strategy means Turkey is likely to stay on the sidelines, analysts here say.

“ISIS is viewed by Turkey as a symptom of the current disorder in Iraq and Syria,” says Sinan Ulgen, director of Istanbul-based think tank the Center for Economics and Foreign Policy Studies, using an acronym for the group. “Unless there is a more long term plan to address the fundamental dynamics, then [Ankara believes] this campaign will not enhance the security of the region.”

Frustration over Washington’s policies in both Syria and Iraq has been festering in Ankara, NATO’s only Muslim-majority member, since the Iraq war of 2003. Back then, Turkey similarly spurned American overtures to station troops in the country and use its airbases.

Ankara’s agenda

Ankara had long been uneasy with Washington’s past backing of former Iraqi Prime Minister Nouri al-Maliki, who was replaced last month by Haider al-Abadi, a fellow member of Maliki’s Shiite Islamist Dawa Party. The sectarian policies of Maliki have been blamed by many Sunnis in the region, including in Turkey, for the rise of IS.

In Syria, Turkey was an eager advocate of early Western intervention to topple President Bashar al-Assad following the 2011 uprising against him, something the Obama administration shied away from. Ankara blamed Assad’s repressive policies for helping IS to gain strength.

“Because the US hasn’t heeded any of these warnings, that explains the reluctance you see from Ankara to be a part of this coalition,” says Ulgen, a former Turkish diplomat.

Turkey has more immediate reasons to be stay its hand. In June, IS militants seized 49 hostages from Turkey’s consulate in Mosul after Iraqi defenses collapsed. The captives include the Turkish consul general and three children.

Meanwhile, media reports in recent days have claimed IS has an extensive recruiting network in Turkey, prompting fears that it could easily strike at Turkish interests if provoked.

Turks for Islamic State

Turkey shares 750 miles of border with Syria and Iraq, and hosts more than one million Syrian refugees. Officials last month admitted they do not know how many Turks are fighting for IS, but said the figure is likely to be higher than 1,000.

Critics say Ankara’s open border policy with Syria allowed guns and foreign fighters to flow across the border, indirectly fueling IS.

While Western states have not accused Turkey of supporting IS, Francis Ricciardone, who served as US ambassador to Ankara until June this year, last week told journalists that Turkey had worked with Jabhat al-Nusra, al Qaeda’s Syrian affiliate, despite Washington’s protests.

“Turkey was late to the party in terms of viewing ISIS as a threat,” says Aaron Stein, a fellow at the Royal United Services Institute, a London-based think tank. “For far too long they took a hands-off approach to the group because their hatred for Bashar al-Assad clouded their judgment.”

The Mosul hostage crisis has changed that, he added, and in recent weeks Western officials have said that Turkey has cracked down on IS’s lucrative cross-border fuel-smuggling trade, and on the flow of foreign fighters across its border.

“They’re sane enough to know that ISIS is a threat to Turkey,” says Asli Aydintasbas, a foreign affairs columnist at the daily Milliyet newspaper, who says Ankara is doing more to combat the group than its public rhetoric suggests.

“I don’t think they’re unhappy [about the coalition],” she said. “On the contrary, they want the Americans to take care of ISIS, but they don’t want to have their fingerprints on it.

“They believe the easiest and safest approach is to send the message: ‘if you don’t mess with us, we won’t mess with you’.”

This post originally appeared in The Christian Science Monitor