WASHINGTON / President Joe Biden will observe next month’s 22nd anniversary of the worst terrorist attack on U.S. soil at an Alaska military base with service members and their families, the White House announced.

Biden will not participate in any of the observances at 9/11 memorial sites in New York City, Virginia or Pennsylvania. Instead, the president will stop in Alaska for a Sept. 11 observance at Joint Base Elmendorf-Richardson in Anchorage on his way back to Washington after a trip to Asia.

Biden is scheduled to travel to India from Sept. 7-10 to attend a summit with other world leaders, followed by a stop in Vietnam.

Vice President Kamala Harris and her husband, Doug Emhoff, will participate in the annual observance at the National September 11 Memorial and Museum in lower Manhattan.

First lady Jill Biden will lay a wreath at the 9/11 memorial at the Pentagon.Terrorists hijacked commercial airplanes on Sept. 11, 2001, and flew them into the Twin Towers in New York’s financial district and the Pentagon in Arlington, Virginia. A fourth plane crashed in a field in Shanksville, Pennsylvania, after passengers fought back.

Nearly 3,000 people were killed in the attacks. Biden was a U.S. senator at the time.It will not be the first time that a president has not attended annual observances at any of the three sites.

In 2015, President Barack Obama participated in a moment of silence on the White House lawn before going to Fort Meade in Maryland to recognize the military’s work protecting the country.

In 2005, President George W. Bush marked the anniversary on the White House lawn.

The White House did not announce which official will participate in the Pennsylvania observance. Associated Press News Researcher Jennifer Farrar in New York contributed to this report.