Pakistan summoned the US Chargé d’Affaires in Islamabad on Tuesday to protest President Donald Trump’s criticism of Pakistan’s role in fighting terrorism and the killing of Osama bin Laden.

Trump’s comments over the last few days have angered Pakistan, including Prime Minister Imran Khan, who on Monday hit back by saying on Twitter that few allies had sacrificed or helped the United States as much as Pakistan in its war on terror, suffering 75,000 casualties.

The friction threatens to worsen already fragile relations between Islamabad and Washington, on-off allies which have repeatedly clashed over the war in Afghanistan and Pakistan’s alleged support for Islamist militants.

Foreign Secretary Tehmina Janjua called in US envoy Paul Jones “to register a strong protest on the unwarranted and unsubstantiated allegations made against Pakistan”, Pakistan’s Foreign Ministry said in a statement.

Over the weekend, Trump said in an interview Pakistan doesn’t “do a damn thing” for the United States despite billions of dollars in U.S. aid, and alleged Pakistani officials knew of former al Qaeda leader bin Laden’s location before his killing by US troops in a raid inside Pakistan in 2011.

On Monday, Trump tweeted again and doubled down on those claims.

“Rejecting the insinuations about OBL, Foreign Secretary reminded the US (Chargé d’Affaires) that it was Pakistan’s intelligence cooperation that provided the initial evidence to trace the whereabouts of OBL,” the ministry said.

On Tuesday, Pakistan army chief Qamar Javed Bajwa, without mentioning Trump, said “Pakistan has done much more for peace in Afghanistan” than any other country.

“We have paid the highest military, economic, political and social cost and the world should acknowledge that,” Bajwa added, according to comments released by military spokesman Major General Asif Ghafoor.