Iran is not being subtle. 

In exercises in one of the world's most strategic waterways, it left little doubt of its capabilities with missile strikes on dummy targets and simulated tanker seizures.

Supreme Leader Ayatollah Ali Khamenei wasn't mincing his words either.

"A warship is a dangerous device," he said. "But more dangerous than that is a weapon that can send that warship deep under the sea."

A fifth of the world's oil supply passes through the Strait of Hormuz, and Iran's exercises have closed it, albeit temporarily, giving a clear sense of what could be to come if the US strikes Iran.

Just a few hundred miles east, a formidable array of US military forces is also amassing.

Read more: Iran and US agree 'guiding principles' after talks

The USS Lincoln aircraft carrier strike group has been conducting exercises of its own. The kind you only carry out if you are preparing for offensive action.

A stretch of water the world relies on for 20% of its oil is becoming cluttered with rival navies, both drilling for war. What could possibly go wrong?

So, what are the chances of diplomacy averting the chances of conflict?

Iran's foreign minister, Abbas Araghchi, emerged from talks sounding hopeful. He's optimistic that the basis for future negotiations has been laid, but warned that an agreement could still be a long way off.

A seasoned diplomat and veteran of negotiations with the West, he cannot afford to look obstructive. The Iranians will want to play for time.

US President Donald Trump has said failure to do a deal could lead to strikes on Iran.

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But the Iranians say a deal on the terms that Trump is currently proposing would be tantamount to surrender. Giving up its nuclear enrichment completely is a red line. Trump says it's a prerequisite.

Squaring that, and many other circles, will be fiendishly difficult.

Without progress, the region is undoubtedly moving closer to war.

(c) Sky News 2026: Middle East seemingly edging closer to war as Donald Trump moves warships -