Col. John Lehane, who took command of the 3rd Marine Littoral Regiment at a Thursday morning ceremony at Marine Corps Base Hawaii, has been getting lots of phone calls since taking over the Kaneohe-­based unit.

“So much so that my phone stopped working and bricked for a little bit,” he told attendees at the ceremony. But he said there was one call from a general that called to congratulate him that stuck with him.

“He said, ‘you know something John, you’re gonna have to have that unit ready for combat, and there’s a good chance it’s going to happen on your tenure,’” said Lehane. “So I want to take an opportunity to publicly acknowledge that I understand that, and I will do everything I can to make sure these Marines and sailors are ready for that occasion should we be called to do so.”

The 3rd MLR officially activated last year and is the first unit of its kind. It is meant to serve as a blueprint for an ambitious Marine Corps plan to restructure its entire force amid boiling geopolitical tensions between the U.S. and China. Under an initiative called Force Design 2030, service leaders envision the Corps returning to its roots as a naval fighting force focused on the sorts of coastal and island operations it conducted in the Pacific during World War II, but with a 21st century twist.

Col. Timothy Brady, the outgoing commander, said that his Marines have worked hard at “thinking about what it means to be a Marine Littoral Regiment and how we’re going to have to see the fight and flight differently than an infantry regiment.”

Brady will be staying on Oahu, taking on a new position at Marine Forces Pacific at Camp Smith as the service continues to refine its vision for the Pacific while Lehane takes over the MLR. Lehane’s most recent assignment was aboard the USS Blue Ridge as the Navy 7th Fleet’s maritime operations director. Marine Corps leaders believe that experience makes him ideal for weaving the MLR into Navy operations and working with the other services.

Marine Corps brass want to see a leaner force that is more agile and adaptable, moving quickly across island chains while also packing a heavy punch. Among the changes is an ongoing effort to phase out all the Marines’ traditional cannon-based artillery on Oahu to replace them with new ballistic missiles that commanders hope to use to sink enemy ships from batteries Marines would set up on islands and coastlines as they support U.S. Navy operations and allied forces.

The new design is geared largely with the Western Pacific in mind. A particular focus is the South China Sea, a busy waterway that nearly one-third of all global trade travels through. China claims nearly the entire sea as its exclusive territory over the objections of neighboring countries, and tensions are mounting over territorial and navigation rights.

In 2016, an international court ruled in favor of the Philippines and found that China’s claims have “no legal” basis. Beijing rejected the ruling and has doubled down by building bases on disputed islands and reefs. The Chinese military has harassed and sometimes attacked fishermen and other marine workers from neighboring countries.

For its part, the U.S. and its allies have been sailing warships through the region conducting “freedom of navigation operations.” Earlier this month a Chinese navy vessel cut across the path of Pearl Harbor-based Navy destroyer USS Chung-Hoon as it was conducting an exercise in the Taiwan Strait with a Canadian ship, forcing it to slow down to avoid a collision.

Beijing considers self-ruled Taiwan a rogue province, and Chinese leader Xi Jinpeng has vowed to bring it under its control by military force if necessary. The island is a major trade partner for the U.S. and a key provider of semiconductors that many American companies depend on to make their products work.

The 3rd MLR has conducted several training exercises across the region. Maj. Gen. Jay Bargeron, commander of the 3rd Marine Division in Japan — of which the 3rd MLR is a part — said that the unit has gone “from concept to reality — from the conceptual unit to a combat credible unit — in what I consider to be a pretty amazing, incredibly short period of time.”

However, not all the pieces Marine Corps leaders want are in place as they push forward with Force Design 2030.

Marines in Hawaii are supposed to be the first to receive new Light Amphibious Warships, which would be crewed by a mixture of Marines and Navy sailors to carry troops and equipment to shore. But Marine Corps and Navy leaders are currently fighting over funding priorities. Marine Corps commandant Gen. David Berger has publicly expressed frustration that ships supporting amphibious operation aren’t getting sufficient funding.

Even so, Marine forces in Hawaii are beginning to look a lot different than they did two years ago.

Among the most notable changes has been the departure of all the Marines’ traditional helicopters from Oahu to replace them with ones that support long-range flight operations. Last month, outgoing MCBH base commander Col. Speros Koumparakis said that rather than having “aircraft that fly around Hawaii,” Marines on Oahu can now “depart today and, in less than 36 hours, be with our partners and allies in the first and second island chains.”

Earlier this year in the Philippines during Exercise Balikatan 2023, troops from the 3rd MLR and the Army’s Schofield Barracks-based 25th Infantry Division trained with the U.S. Navy and Philippines marines conducting island operations in the Luzon Strait just south of Taiwan.

During the exercise they also conducted a live-fire coastal defense exercise as well as a ship-sinking exercise off the west coast of the Philippines. Brady said “we brought more than 1,300, the entirety of the MLR, forward into the first island chain where we are relevant, where we can do our mission, where we can get after (it).”

The seeming breakdown in U.S.-China relations has fueled deep unease in the region. On Monday, the New York-based Eurasia Group Foundation released the results of a survey that found that about 81% of people in the Philippines and 67% of South Koreans think rising tensions between China and the U.S. are likely to endanger their own national security.

Regional leaders have urged Chinese and American officials to turn down the temperature on tensions. At a recent international defense and diplomacy summit in Singapore, Chinese officials repeatedly refused to meet with American counterparts, though some reports suggest informal talks between the two did occur. This week U.S. Secretary of State Anthony Blinken is set to arrive in China in an effort to stabilize the relationship.