The Iran war now has a price tag ($25 billion), but still no end date

The Pentagon says it hit some 13,000 targets in Iran before Trump declared a ceasefire on April 7.

Hurst's testimony marked the first time the Trump administration has publicly offered a cost estimate on the war.

The Iran war dominated the hearing, which was scheduled to discuss the Pentagon's budget for next year. The Trump administration is asking for around $1.5 trillion, a massive increase from this year's allocation of a little under $1 trillion.

A diplomatic stalemate

While the ceasefire with Iran has been in place for three weeks, there's been little progress on a diplomatic solution.

U.S. and Iranian negotiators have held only one formal round of talks, though they've been exchanging messages and proposals through Pakistan, which has served as a mediator.

The U.S. and Iran are waging dueling blockades of the Gulf, effectively bringing a halt to oil and other commercial traffic. This has dramatically pushed up oil prices and causing economic hardship worldwide.

Iran cut off the Strait of Hormuz in the early days of the war, relying on small weapons, such as mines at sea, or drones and missiles from land. The U.S. countered on April 13 with its own blockade enforced with a large naval presence.

U.S. capabilities in the Gulf

Kevin Donegan, a retired U.S. Navy vice admiral who previously commanded the U.S. Fifth Fleet, based in Gulf nation of Bahrain, said he believed the U.S. could keep the current blockade going indefinitely.

"It's very sustainable with the forces they have in the region now," Donegan told NPR. "They can even peel some of (those ships) back and move others into the region to do a rotation."

Donegan said a negotiated agreement would be the best, safest way to reopen the strait. But he said the U.S. Navy can clear the waterway, though it would take time to remove mines and further degrade Iran's forces on land.

Donegan, who's now at the Middle East Institute think tank in Washington, said he doesn't know precisely what steps the military is taking. But based on his experience, he believes the U.S. is using unmanned vessels – above and below the surface -- to clear mines.

The underwater vessels, he said, "look like big torpedoes. They can find any mines that are there, and then there are other remote vehicles that can then remove them. You basically open up two good passageways, one coming in, one coming out."

If asked, the Navy could escort oil tankers through the strait, he added. But there would be risks and the number of ships passing through would likely be well below the pre-war shipping traffic.

Before the war, more than a 100 commercial ships sailed through the strait daily, going to and from Iran, as well as Arab countries, carrying oil, natural gas and other key components for the global economy.

"You'd obviously start doing that with small numbers (of ships) and you're going to have to diminish any residual capability the Iranians have," Donegan said. "Let's say you finally did get to where you can move convoys back and forth, and now you're going to have a much, much reduced capability than it normally would be."

The U.S. has had a naval presence in Gulf since 1949, and the Fifth Fleet was formally established in Bahrain in 1995 specifically to protect the flow of oil.

Donegan said that when he was commanding the Fifth Fleet a decade ago, he was often thinking about the possibility of Iran closing down the Strait of Hormuz.

"It's at the forefront of everything that we did in the Fifth Fleet, knowing that if we carried out military operations, this would be a card that the Iranians would play," he said. "It's completely expected that this is what they would do and is built into your planning process."

Despite the decades of turmoil in the Middle East, the flow of oil in the Gulf has never faced such a comprehensive shutdown. The last significant disruption was during the 1991 Gulf war when a U.S.-led coalition forced Iraqi troops out of Kuwait.