BRUSSELS (AP) — President Donald Trump is participating in a welcome ceremony with fellow NATO leaders at what’s expected to be a fraught meeting of the military alliance.

Trump was spotted chatting with British Prime Minister Theresa May and Turkish President Recep Tayyip Erdogan (REH’-jehp TY’-ihp UR’-doh-wahn) during public portions of the opening.

But he appeared to steer clear of German Chancellor Angela Merkel hours after claiming her country was controlled by Russia. He also walked far behind the leaders of the U.K. and Canada during a walking tour of NATO headquarters.

NATO Secretary General Jens Stoltenberg (yehnz STOHL’-tehn-burg) is stressing the need for the allies to stick together, saying, “We owe our success to our unity.”