Families of 143 American troops and contractors killed or wounded in Afghanistan have sued U.S. and international contractors involved in Afghan reconstruction projects for allegedly paying protection money to the Taliban.The lawsuit, filed Friday in federal court, claims certain contracting companies often paid the Taliban through subcontractors, which allowed the the companies to save money on security personnel. The Taliban then used the money, according to the lawsuit, to fund attacks on other companies that didn't make payments to the insurgent group."The defendants are large corporations that had lucrative businesses in Afghanistan," said Joshua Branson, a lawyer for the case, in a statement to the Wall Street Journal. "Those protection payments, as alleged, redirected attacks away from the defendants’ own interests while financing a terrorist insurgency that killed and injured thousands of Americans, including our clients."It has been widely known for years that money from American defense contractors has found its way to local Afghan warlords in the wake of the U.S. invasion of the country. A 2010 congressional investigation found that funds from Pentagon-backed contractors were fueling a "protection racket" by bribing local officials and possibly Taliban members in exchange for safe passage of goods.No U.S. or international companies have been successfully prosecuted for aiding the Taliban. The current lawsuit is a civil suit, which will enable a conviction if prosecutors can convince a jury of a preponderance of evidence in their favor, as opposed to a criminal suit which requires proof beyond a reasonable doubt.The war in Afghanistan, now 18 years old, came under increased scrutiny after the Washington Post published a trove of documents it dubbed the "Afganistan Papers." The records are from a federal investigation into the war effort and contain reflections of U.S. officials and troops in which they express doubts about the success of the war and the clarity of the military's mission. The officials also indicated the U.S. repeatedly misrepresented progress in the war to the government and the American people.The U.S. has been attempting peace negotiations with the Taliban, but talks have proceeded slowly as insurgents have continued to attack American targets.