By John Davison BAGHDAD (Reuters) – Billed by Tehran as a warning to Israel, Sunday’s attack on an Iraqi city was also a pointed reminder of Iran’s armed clout for its U.S. and Arab foes at a delicate moment for the Islamic Republic, Iraqi and Western officials and independent analysts say. The unusual direct strike coincides with a potential turning point in the Middle East balance of power, as talks to revive an Iranian nuclear deal face possible collapse and heightened risks of war in the Gulf, while in Baghdad, Iraqi leaders are trying to form a new government shorn of Iranian influence. B…