The USS Abraham Lincoln aircraft carrier strike group has crossed into Central Command, the Middle East region that includes Iran, a U.S. official told CBS News.

The movement comes days after Iran’s Revolutionary Guard commander warned that his force had its “finger on the trigger,” as the U.S. warships moved toward the region.

The strike group is comprised of the Lincoln, an aircraft carrier, and three guided missile destroyers: the USS Frank E. Petersen, Jr., the USS Spruance and the USS Michael Murphy. On board the Lincoln are squadrons of F/A-18E/F Super Hornets, EA-18G Growlers, F-35C fighter jets and MH-60R/S helicopters.

The naval force was not necessarily “on station” as of Monday morning Eastern Time, meaning it was not in its intended ultimate position.

President Trump said on Thursday that the U.S. had a “massive fleet” heading toward Iran “just in case” he wants to take action, although he added, “maybe we won’t have to use it.” 

Mr. Trump has repeatedly warned Iranian leaders against the killing of peaceful demonstrators — who started protesting in late December in the largest challenge to the country’s ruling regime in years — and the mass execution of people arrested in the protests.

Over the weekend, Nournews, a news outlet close to Iran’s Supreme National Security Council, reported on its Telegram channel that Gen. Mohammad Pakpour warned the U.S. and Israel “to avoid any miscalculation.”

“The Islamic Revolutionary Guards and dear Iran stand more ready than ever, finger on the trigger, to execute the orders and directives of the Commander-in-Chief,” Pakpour was quoted as saying, The Associated Press reported.