Troops of a task force of the 17th Infantry Regiment scrambled to get to the mountainous area where the aircraft was believed to have crashlanded, he said.
Tuanyuan, named after the Chinese word for reunion, releases information about missing children and was developed for the authorities by e-commerce giant Alibaba.
Trump strode into the White House briefing room on Thursday, the 13th day of the partial government shutdown, and declared that "without a wall you cannot have border security". He then left without taking questions from reporters.
Trump and the first lady later returned to the balcony toward the end of a nationally televised concert from the South Lawn and stayed for the annual fireworks show on the National Mall. Trump pumped both fists several times at the end of the show before he went back inside the White House.
Trump has said he is America's most pro-Israel president and pointed to his decisions to recognize Jerusalem as the capital, move the American embassy to the holy city from Tel Aviv, and recognize Israeli sovereignty over the Golan Heights.
Trump has vowed to return to campaigning shortly and to participate in the second presidential debate against opponent Joe Biden in Miami on October 15.
张家口烤瓷牙坏了怎么换
Trump says governors should 'dominate' streets amid protests
Trump, meanwhile, was described as attacking his Attorney General Jeff Sessions as "a traitor" for recusing himself in the Russian investigation. He also belittled Sessions as "mentally retarded" and a "dumb southerner".
Trump threatened Iran in a tweet on Sunday, raising concerns about a potential US-Iran conflict at a time when tensions between Washington and Tehran have risen.
Trump is expected to inform Congress as early as Friday, several media outlets quoted anonymous White House sources as saying.