By Reuters  The White House sent to Congress on Saturday formal notification of Friday’s U.S. drone strike that killed a top Iranian general, congressional aides said, amid complaints from Democrats that President Donald Trump did not notify lawmakers or seek advance approval for the attack. The U.S. strike that killed Iranian military commander Qassem Soleimani in Iraq has caused a dramatic rise in tensions between Iran and the United States and its allies. The notification was sent under a 1973 U.S. law called the War Powers Act, which requires the administration to notify Congress within 48 hours of committing armed forces to military action or imminent actions. Trump’s administration was expected to explain the circumstances, the authority under which the action was taken and the expected scope and duration of the military involvement. The White House declined to comment. The version submitted to Congress is classified and it is not clear if the White House will release an unclassified version, two senior congressional aides said, speaking on condition of anonymity. Senator Bernie Sanders, a contender among Democrats seeking to run against Trump in November’s presidential election, said on Saturday that Congress must take immediate steps to restrain Trump “from plunging our nation into yet another endless war.” Senator Elizabeth Warren, another Democratic candidate, told reporters on Saturday that Trump has taken the United States “to the brink of war” and called his actions “reckless. He evidently has no plan.” House of Representatives Speaker Nancy Pelosi has said the strike in Baghdad was conducted without specific authorization from Congress and “without the consultation of the Congress.” The Pentagon on Friday briefed staff members from the House Armed Service Committee and Senate Armed Service Committee on the attack and other recent developments in Iraq. On Friday, Democratic U.S. Senator Tim Kaine introduced a resolution to force a debate and vote in Congress to prevent further escalation of hostilities with Iran. Democratic Senator Chris Murphy wrote on Twitter that “even if there was an ‘imminent attack’ it’s insane to argue that gives the President legal carte blanche to take any and all military actions.” Republicans in Congress have generally backed Trump’s action. Senate Republican Leader Mitch McConnell said on Friday that “no man alive was more directly responsible for the deaths of more American servicemembers than Qassem Soleimani.”