The slaying in Bangladesh of a U.S. Agency for International Development employee has intensified U.S. concern that the strategically located South Asian country with traditions of religious tolerance is under threat from Islamic extremists.

Bangladesh's government denies that transnational jihadist groups have been behind a spate of bloody attacks on secular writers, bloggers, foreigners and religious minorities. But the Bangladeshi branch of al-Qaida on the Indian Subcontinent claimed Monday's killing of USAID employee and gay rights activist Xulhaz Mannan.

That claim has not been verified, but it adds to fears that local extremists with international aspirations could enable groups like al-Qaida and the Islamic State group to gain a foothold in a country wracked by prolonged political turmoil.