Kremlin spokesperson Dmitry Peskov said on Friday that President Vladimir Putin and Saudi Arabia’s King Salman had discussed military cooperation in talks on Thursday and said other countries should not worry about such ties.

“Work on this will be continued,” Peskov told reporters on a conference call. “The improvement of military cooperation between Russia and Saudi Arabia … is not directed against a third party and we believe it’s groundless to express concern about this issue.”

On Thursday, Saudi Arabia has agreed to buy Russian S-400 surface-to-air missile systems, Saudi-owned al Arabiya television reported.

The countries also signed a memorandum of understanding to help the kingdom in its efforts to develop its own military industries, a statement from state-owned Saudi Arabian Military Industries said.