U.S. Army Secretary Dan Driscoll wants to finalize a deal with Hawaiʻi by the end of the year to continue the Army’s access to thousands of acres of training lands on Oʻahu and the Big Island, Driscoll wrote in a letter to Gov. Josh Green Thursday.

Part of the deal could include land exchanges, Driscoll wrote, without offering specifics. His letter comes months after the Army hit a stumbling block when the state land board rejected environmental studies that were a prerequisite for the military to retain leases it has held with the state since 1965, which has allowed soldiers to train on lands in Waiʻanae, on the North Shore and in the Pōhakuloa artillery range on Hawaiʻi island.

Military leaders believe those lands are necessary to counter growing threats from China and Russia.

Green has said he wants a “fair deal” from the federal government for use of those lands. But in a written statement Thursday, the governor seemed to acknowledge that Hawaiʻi has little leverage over federal leaders who could simply take the land.

“Federal leaders have stated there are national security considerations at stake and they’ve made clear they could act through eminent domain, which would take the land without giving Hawaiʻi anything in return,” Green said in a news release. “We in Hawai‘i know the best path is always through collaboration which acknowledges our values.”

Green, a Democrat who has touted a positive relationship with President Donald Trump, called for state lands in Mākua to return to the state and said that the military should be responsible for cleaning contaminated areas.

He also wants a commitment that the federal government would build homes in the state and transfer lands to the state Department of Hawaiian Home Lands. The agency is responsible for implementing a century-old act of Congress that mandates housing for Native Hawaiians who meet blood quantum requirements. But it has been hampered by a lack of funding and usable land.

“While some may say we are being too accommodating, the truth is this path ensures that Hawaiʻi’s people and values come first,” Green said. “By negotiating firmly and fairly, we can secure real benefits for our future while maintaining national security.”

What exactly the negotiations may yield, whether it be land or money, isn’t yet clear: Like Driscoll’s letter, Green’s statement was light on details.

The federal government owns more than 829,000 acres in Hawaiʻi — about 20% of land in the state — but those are predominantly nature preserves or active military bases. The military also owns lands with housing that is already occupied by military families.

In the past 20 years, the Army has significantly scaled back its use of state lands by ending live-fire trainings and mostly conducting exercises that involve aircraft.

However, it continues to use the Pōhakuloa Training Area for long-range artillery training. It’s the only site of its kind in the Pacific. Driscoll’s letter said that losing access to training areas would “create a vulnerability that we, as a nation, cannot afford.”

“While we always hope for peace, we must plan for war,” he wrote.

Green’s office is still in negotiations and intends to issue a formal response to the Army in the weeks ahead, his statement said. The governor’s office also plans to make formal documents received from the Army publicly available on a new website.