Trump's latest threat 'extremely hard to justify' under international law: expert

President Donald Trump's latest threat against the Iranian regime is "extremely hard to justify" under international law, according to one expert.

Admiral James G. Stavridis told CNN's Abby Phillip on "The Arena" on Monday that Trump's threat to bomb Iran's water and energy infrastructure if the country does not reopen the Strait of Hormuz would be a difficult move to defend. Certain parts of the threat seem to align with international law, but attacking civilian infrastructure could extend the war in Iran for years to come, he added.

"So striking oil. No, I don't see that as illegal under international law," Stavridis said. "The electric grid is kind of in a gray area. It depends on whether you are striking portions of it that supported military activity, or going after the water supplies, which would be extremely hard to justify under international law."

Trump has tried for several weeks to get the Iranian regime to reopen the Strait of Hormuz, and so far those efforts have come up short. The waterway is responsible for roughly 20% of global energy trade, and its closure is one reason why gas prices in the U.S. have skyrocketed since the war in Iran began.

Stavridis added that striking Iran's water infrastructure could cause a ripple effect in the region.

"Leaving aside the legalities ... the practical effect would be batteries released against the Gulf Arabs' desalination plant. So if this thing turns into a water war, it's going to take years for the region to come back," he said.