The Peshawar High Court had on May 9 declared the CIA drone strikes targeting suspected Taliban and al Qaeda militants to be a "war crime" and ordered Islamabad to take steps to halt them.Victims' families and their lawyer Mirza Shahzad Akbar have written to Sharif urging him to heed the court's ruling, which calls on the government to take the matter up at the UN Security Council.While Islamabad regularly issues statements condemning the missile strikes as a violation of sovereignty, it has yet to take any stronger action publicly to pressure Washington to end the campaign, which began in 2004."The court has ordered the government of Pakistan and its security forces to administer a proper warning to the United States that future drone strikes will not be tolerated," Akbar wrote in the letter, seen by AFP.Akbar said that if Pakistan failed to persuade the US to stop the strikes through the United Nations, "the court has very clearly ordered to shoot down the drones".At a news conference with two relatives of drone victims, Akbar warned that Sharif would face contempt of court proceedings if he did not implement the court order within 14 days.Mohammad Nazir, whose son was killed in a US drone strike in June 2006 in North Waziristan tribal district, a haven for insurgents, endorsed the demand and said he wanted revenge for his son's death."My son was 25 years old, he was a labourer and was working in a house with other labourers in the night when the drone strike took place," he told AFP."According to tribal law, you kill the son of that person who kills your son, so I will take revenge of my son's killing whenever I have the opportunity."According to the British Bureau of Investigative Journalism, since 2004 up to 3,587 people have been killed in Pakistan by drone attacks, which Washington says are an effective weapon in the fight against Islamist militancy.On Wednesday Sharif used his first speech as prime minister to urge the US to end the strikes and said a comprehensive strategy for tackling extremism should be worked out.