Senate Majority Leader Mitch McConnell on Friday ripped President Trump’s decision to withdraw American troops from Syria, calling it “a grave strategic mistake.”

Writing in an op-ed for The Washington Post, McConnell — a hardcore, longstanding Trump loyalist — said the move diminishes US influence across the globe and emboldens US enemies — including terrorist groups.

“There is no substitute for American leadership. No other nation can match our capability to spearhead multinational campaigns that can defeat terrorists and help stabilize the region,” McConnell wrote in the op-ed published Friday afternoon.

“Events of the past week have set back the United States’ campaign against the Islamic State and other terrorists,” McConnell added. “Unless halted, our retreat will invite the brutal Assad regime in Syria and its Iranian backers to expand their influence.”

McConnell was responding to Trump’s decision to pull a small number of US troops out of Northeast Syria, clearing the way for Turkey to invade the country and massacre Kurds who live in the area.

Russia capitalized on the US retreat, McConnell added, by exerting its influence where American troops once occupied.

“Predictably, our adversaries seem to be relishing these developments,” McConnell wrote.

“The resulting geopolitical chain reaction appears to have been perfectly distilled by an online video which, according to reports, shows a smiling Russian “journalist” strolling around a just-abandoned U.S. military base in northern Syria,” he added.

McConnell is not the only GOP senator to criticize Trump for the retreat.

On Thursday, Mitt Romney slammed the decision from the Senate floor, saying “the decision to abandon the Kurds violates one of our most sacred duties.”