Iran, July 7 -- A top aide to Iran's supreme leader says the Islamic Republic is ready to enrich uranium beyond the level set by Tehran's 2015 nuclear deal, just ahead of a deadline it set Sunday for Europe to offer new terms to the accord.

A video message by Ali Akbar Velayati included him saying that "Americans directly and Europeans indirectly violated the deal," part of Tehran's hardening tone with Europe. European parties to the deal have yet to offer a way for Iran to avoid the sweeping economic sanctions imposed by President Donald Trump since he pulled the U.S. out of the accord a year ago, especially those targeting its crucial oil sales.

All this comes as America has rushed thousands of troops, an aircraft carrier, nuclear-cap...