Jared Kushner, President Trump’s son-in-law, landed in Iraq on Monday, military officials said, visiting the country as the American military is aiding Iraqi forces in their brutal fight to retake Mosul from the Islamic State.

It was unclear what Mr. Kushner, who has been expanding his reach in his father-in-law’s administration, planned to gain from the trip. Mr. Kushner, 36, who serves as a senior adviser to Mr. Trump, was invited by Gen. Joseph F. Dunford Jr., the chairman of the Joint Chiefs of Staff.

Navy Capt. Greg Hicks, a spokesman for the chairman, said early Monday that the general had arrived in Iraq for meetings, including with coalition officials, accompanied by Mr. Kushner and Thomas P. Bossert, the president’s homeland security adviser.

The general invited Mr. Kushner and Mr. Bossert to accompany him “to receive an update on the status of the counter-ISIS campaign in Iraq and Syria,” Captain Hicks said.