Islamabad: A five-member US delegation on Friday met Pakistan's top Foreign Affairs Advisor Sartaj Aziz amid relations between the two countries hitting a low after a US drone strike killed Taliban leader Mullah Akhtar Mansour in Balochistan province. The meeting discussed regional security issues and US drone strike in Noshki area, a Foreign Office statement confirmed. The US delegation was told that the "drone strike was an attack on sovereignty of Pakistan and violation of UN Charter", the Foreign Office statement reads. Future drone strike will affect Pakistan-US relationship, the statement added. The US delegation maintained that they would make efforts to improve the strained relationship. "The US is determined for better relationship with Pakistan," Senior Director for South Asian Affairs at the National Security Council Peter Lavoy, who led the delegation, said. The delegation also included US Special Representative for Afghanistan and Pakistan Richard Olson. The Pakistan delegation was led by Sartaj Aziz. The US team will also hold important meetings with other officials including army chief General Raheel Sharif and National Security Adviser Lt.Gen. (retd) Nasser Khan Janjua. With senior foreign policy and military officials privately questioning if the US truly desires a stable Pakistan, the visiting delegation will have perhaps the toughest meetings between the two sides since Osama bin Laden was killed in a secret US operation at Abbottabad, near Islamabad.