teran Republican Senator John McCain on Tuesday slammed as "deeply disturbing" allegations that US President Donald Trump had shared top secret intelligence about the Islamic State group with Russian officials.
McCain -- one of the president's most outspoken critics in his own party and the chairman of the Senate Armed Services Committee -- added his voice to a growing chorus of alarm triggered by Monday's report in the Washington Post.
"The reports that the president shared sensitive intelligence with Russian officials are deeply disturbing," McCain said in a statement.
"Reports that this information was provided by a US ally and shared without its knowledge sends a troubling signal to America's allies and partners around the world and may impair their willingness to share intelligence with us in the future."
The Republican senator, who takes a hawkish line towards Moscow, regretted that "the time president Trump spent sharing sensitive information with the Russians was time he did not spend focusing on Russia's aggressive behavior."
McCain said that behavior included "interference in American and European elections, its illegal invasion of Ukraine and annexation of Crimea, its other destabilizing activities across Europe, and the slaughter of innocent civilians and targeting of hospitals in Syria."
According to the Post, Trump revealed highly classified details of an IS terror threat during a meeting last week with Russian Foreign Minister Sergei Lavrov and Moscow's ambassador in Washington, Sergey Kislyak.
The information reportedly came from a US ally who had not authorized Washington to share it with Moscow.
Trump hit back on Twitter early Tuesday, claiming the "absolute right" to share "facts" with Russia.
But on Capitol Hill, lawmakers on both sides of the political aisle voiced astonishment at the allegations.
"If the report is true, it is very disturbing," warned the top Democrat in the Senate, Chuck Schumer.
"Revealing classified information at this level is extremely dangerous and puts at risk the lives of Americans and those who gather intelligence for our country."
"The president owes the intelligence community, the American people, and Congress a full explanation," said Schumer, who has asked for the transcript of Trump's meeting with the Russia officials to be made available to Congress.
House Speaker Paul Ryan has also asked for a "full explanation," a spokesman said.