State Department spokeswoman Morgan Ortagus said the US has expressed to the Turkish government that the acquisition of Russian military systems such as the S-400 is unacceptable.
The tests last year were already known, so Russia’s agenda of discussing them again may be linked to a wider one.
Making the S-400s operational exposes Turkey to US sanctions under legislation designed to punish countries which buy defense equipment from Russia.
"The time for patience has long expired," Republican Lindsey Graham and Democrat Chris Van Hollen said.
Qatar’s security and defense cooperation are the backbone of the Doha-Ankara alliance, Erdogan said. “We have deep relations in the Gulf.”
After the much anticipated meeting at the White House to address a crisis in relations, Trump said he was "a great fan" of the Turkish leader and that they had a "productive" encounter.
Republican Senator Rick Scott plans to unveil a resolution on Thursday calling for sanctions against Turkey after its purchase of a Russian air defense system.
Speaking symbolically on the third anniversary of the 2016 attempted coup against him, President Recep Tayyip Erdogan said that eight planes had landed with parts of the S-400.
Erdogan says delivery of system to be completed by April 2020.
US calls move "unacceptable."