WASHINGTON, April 16 (Reuters) - U.S. officials have informed some European counterparts that some previously contracted weapons deliveries are likely to be delayed as the Iran war continues to draw on weapons stocks, five sources familiar with the matter said... Some of the weapons in question were purchased by European countries under the Foreign Military Sales program, or FMS, but have not yet been delivered, the sources added. Those deliveries will likely be delayed, U.S. officials told European officials in bilateral messages in recent days, the sources said.