What We’re Watching: America Rules the Waves & An Istanbul Do-Over

US warships steaming toward Iran – A US aircraft carrier group is now headed to the Middle East following warnings from Washington that Iran and its proxy forces have given "troubling and escalatory" indications of a possible attack on US forces in the region. It's not immediately clear what these indications are, but we're certainly watching for any dangerous escalation in US-Iranian military tensions. Tomorrow marks the one-year anniversary of President Donald Trump's decision to withdraw the US from the Iranian nuclear agreement.

The Istanbul Do-Over – Turkey's President Recep Tayyip Erdogan wanted another chance to win local elections in Istanbul, and he'll get one on June 23. A Turkish court ruled on Monday that a previous vote, which the opposition won by a margin of about 14,000 votes out of more than 8 million cast on March 31, must be re-run. We'll be watching not only for the new election result but for how Erdogan, the opposition, and residents of Istanbul react to them – if you call a do-over, you better be sure to win when it's done over, right?

What We're Ignoring: The UK's Newest Royal & A Deep, Deep Hole

Baby Sussex – The Signal team sends hearty congratulations to the Duke and Duchess of Sussex—that's Prince Harry and Meghan Markle for all you Americans—on the birth of their first child, a boy. But given that this kid is only seventh in line of royal succession, he better be doing card tricks by Thursday or we won't have much further interest in him. (Trivia fans: per our friend Dave Lawler at Axios, seventh in line to the US presidency is Attorney General William Barr — how's that for an expert weaving of news flows?)

Jumping down the deepest hole on Earth – You probably know that there was a Cold War race to the moon, but less familiar is the fierce scramble to the center of the Earth. By the time the USSR fell, Soviet scientists had drilled the deepest hole in the planet, more than 7 miles under the Siberian tundra, in an unfinished bid to reach all the way to the earth's mantle. The Kola Superdeep Hole has been capped since then, but Japanese scientists now want to take the plunge. We are doing our best to ignore this extraordinary story, because we fall down WAY too many fascinating rabbit holes in our line of work as is...