A group of US senators, including the vice chair of the Senate Intelligence committee, received a classified briefing Wednesday about a series of reported encounters by the US Navy with unidentified aircraft, according to a congressional aide. President Donald Trump recently confirmed that he was also briefed on reports of Navy pilots spotting unidentified flying objects. Several pilots told the New York Times in an article published in May about multiple encounters with UFOs with no visible engine or infrared exhaust plumes. In April, the Navy introduced guidelines for its pilots to report unexplainable events so the military can keep track of what may, or may not, be happening. Politico first reported on this matter. A Navy official told CNN at the time that the Navy does not believe aliens have been flying around US airspace. But the Navy said these kinds of “incursions” pose both a security risk and safety hazard.