BUCHAREST, Romania (AP) — Some 5,000 troops from NATO and partner countries are staging exercises in Romania watched by a senior NATO official and Romania's president.

President Klaus Iohannis and NATO Military Committee head Gen. Petr Pavel, who is on a two-day visit to Romania, were welcomed with military honors ahead of Saturday's exercises at the Cincu shooting range in northwest Romania.

Troops from Romania, the U.S., Ukraine, Armenia and Croatia opened gunfire, backed by U.S. and Romanian military aircraft.

The exercises, led by U.S. Army Europe, began this week in Eastern Europe involving 25,000 military personnel from more than 20 allied and partner countries. The U.S. is seeking to reassure NATO's European allies concerned about Russia since it annexed Crimea in 2014.

The exercises run until July 20.