ISLAMABAD: US national security adviser Lieutenant General HR McMaster arrived in Islamabad on Monday on an unannounced visit, a day after he hinted the US could take a tougher stance on Pakistan.It was the first visit by a top member of President Donald Trump 's administration to the militancy-hit South Asian country, and came after a stop in neighbouring Afghanistan where he suggested Washington may take a stronger line on Islamabad, for years seen as an unreliable US ally.Before his visit to Islamabad, McMaster in an interview to Afghan television channel ToloNews appeared to take a "tougher line" on Pakistan, which has been accused of using the Taliban as a proxy force and giving its leaders sanctuary."As all of us have hoped for many, many years — we have hoped that Pakistani leaders will understand that it is in their interest to go after these groups less selectively than they have in the past," McMaster said in the interview."The best way to pursue their interests in Afghanistan and elsewhere is through the use of diplomacy, and not through the use of proxies that engage in violence," McMaster said.In Pakistan, McMaster's gave no interviews and the official statement on his visit was more diplomatically couched."General McMaster expressed appreciation for Pakistan's democratic and economic development, and stressed the need to confront terrorism in all its forms," the U.S. Embassy said in a statement.McMaster met Prime Minister Sharif and Chief of Army Staff General Qamar Javed Bajwa as well as top foreign policy and national security officials."The prime minister conveyed Pakistan's readiness to work with the international community to explore ways in which the Afghan crisis can be resolved," Sharif's office said in a statement.The Pakistani statement added that McMaster's delegation included Lisa Curtis , who US media have previously reported as his pick as senior director for South and Central Asia.Curtis, a well known conversative expert, recently co-authored a paper calling on the US to stop treating Pakistan as an ally and instead "focus on diplomatically isolating" it if it continues to support groups that have links to international terror.US-led NATO troops have been at war in Afghanistan since 2001, after the ousting of the Taliban regime for refusing to hand over Osama bin Laden following the 9/11 attacks in the United States.The US has around 8,400 troops in the country with about another 5,000 from NATO allies, as efforts to negotiate a lasting peace settlement between Kabul and the Taliban have repeatedly fallen through.Afghanistan routinely accuses Pakistan of providing safe haven to the Afghan Taliban.On Thursday the US military in Afghanistan dropped its GBU-43/B Massive Ordnance Air Blast, dubbed the "Mother of All Bombs" in combat for the first time on Islamic State group hideouts, killing up to 95 militants.The attack triggered global shock waves, with some condemning the use of Afghanistan as what they called a testing ground for the weapon, and against a militant group that is not considered as big a threat as the resurgent Taliban.