After more than a decade of planning, delays and controversy, the cutting-edge Thirty Meter Telescope has been issued a “notice to proceed” with construction, state officials said Thursday.

The announcement followed an early morning operation by state law enforcement officers to remove four unauthorized structures from the slopes of Mauna Kea, including two Native Hawaiian ahu, or altars, in the mountain’s northern plateau, the planned site of the telescope.

“We expect that TMT construction will begin sometime this summer,” Gov. David Ige said at a news conference at the state Capitol. “We will proceed in a way that respects the people, place and culture that make Hawaii unique.”

Those who oppose the billion-dollar- plus project immediately denounced the move.

“It’s a sad day in Hawaii,” Native Hawaiian activist Healalani Sonoda-Pale said. “If they’re going to move forward on this project, then we are going to have conflict up on the mauna. There’s no question about it.”

Even before the news conference, TMT foes were upset by the morning’s action on the mountain, when about 20 state vehicles carrying law enforcement officers dismantled structures that included ceremonial platforms for placing flowers, sacred water and other prayer offerings.

The operation occurred on the eve of solstice ceremonies, Mauna Kea Hui leader Kealoha Pisciotta said.

“It’s outrageous,” said an angry Pisciotta. “This state action is desecration, provocation and a hostile and racist act committed against the Hawaiian people and the people of Hawaii. They came in the night like a thief.”

Kahookahi Kanuha, a veteran TMT foe and one of the leaders of the “protectors” who helped stop the TMT in 2015, was arrested near the summit while trying to make a video of officers and officials removing the structures.

Two of the structures were stone ahu built in 2015 at the northern plateau, one on the road and the other on the TMT construction site.

Another structure was the makeshift building constructed across from the Mauna Kea visitors center during TMT protests in 2015, while the other was known as Hale o Kuhio, or the “kanaka ranger station,” on the Mauna Kea Access Road on Hawaiian homelands.

Authorities blocked access on the road to the summit at about 6:45 a.m. “for safety and security” reasons while state personnel and work trucks traveled up and down the mountain to dismantle the ahu structures, said Cindy McMillan, the governor’s communication director.

The Office of Hawaiian Affairs issued a statement expressing disappointment with the arrest and the dismantling of the “symbolic structures on Mauna Kea.”

“These acts and the manner in which they were conducted, with little to no consultation with the Native Hawaiian community and OHA, exemplify the state and UH’s longstanding and blatant disregard of Mauna Kea’s significance to our beneficiaries, whose deep connection to the sacred mountain was embodied by the ahu and hale pili removed today. The failure to consult with the Native Hawaiian community and OHA prevented government officials from fully understanding the mana imbued over years into these structures,” the statement said.

“The absence of these cultural structures has deprived the Mauna of an important contemporary Native Hawaiian cultural presence on this sacred place beset with foreign activities. Today is just another sad chapter in the state and UH’s longstanding mismanagement of Mauna Kea, and only affirms the urgent need for a change in management of Mauna Kea as sought by OHA’s lawsuit against DLNR and the UH.”

Elsewhere, the Hawaii County Council issued a release saying that due to “the tremendous amount of calls and contacts” to its office, it has requested a report on the Mauna Kea operation and the extent to which the Hawaii County Police Department, Corporation Counsel and county administration were involved.

Land Board Chairwoman Suzanne Case said her department issued the “notice to proceed” Wednesday afternoon following a months-long review of the project’s construction and grading plans that were submitted by the applicant, leaseholder University of Hawaii at Hilo, on Feb. 3.

State Attorney General Clare Connors said the state is planning for safe access by construction crews while allowing for free speech and protest. She said law enforcement will be on hand.

“The safety of our community depends upon people respecting the law and each other,” Connors said.

Henry Yang, chairman of the TMT International Observatory board of governors, issued the following statement Thursday:

“TMT is pleased and grateful that the notice to proceed has been issued by the Department of Land and Natural Resources to the University of Hawaii. We remain committed to being good stewards of Maunakea, and to honoring and respecting the culture and traditions of Hawaii. It has been a long process to get to this point. We are deeply grateful to our many friends and community supporters for their advice and for their encouragement and support of the TMT project over the years.”

TMT spokesman Scott Ishikawa said that “while we like to start as soon as possible, we will meet with state and county officials to determine the best time to begin.”

Construction would begin with site preparation and the building of perimeter fencing, he said.

That was the plan four years ago, until it was thwarted by protesters, 31 of whom were arrested for trespassing and blocking vehicles. A second try at construction a few months later ended with more arrests and boulders blocking the road.

Before the end of the year, the Hawaii State Supreme Court would revoke the conservation district use permit after ruling that the Board of Land and Natural Resources erred in approving the permit prior to its contested case hearing.

After another contested case hearing was held, the high court would have the final say once again in October in upholding the construction permit approved by the BLNR in September 2017.

On Thursday UH President David Lassner said the TMT would be the last telescope built on Mauna Kea’s summit. He said five current telescopes would be decommissioned and their sites restored.

“We know there are members of the community, including within the University of Hawaii, who oppose this project. We are truly sorry for the pain some of them feel, and we fully respect their rights under the First Amendment to protest in a peaceful and lawful manner,” he said.

Ige said he continues to support Hawaii island Mayor Harry Kim’s vision for Mauna Kea as an international peace park, “and I will continue to work with the University of Hawaii to make meaningful changes that further contribute to the culture and science on Mauna Kea.”

Ige alluded to the violent Standing Rock Dakota Access Pipeline protests while urging protesters to express themselves peacefully.

“To those of you from outside Hawaii or even outside Hawaii island who take a position on this project, please respect our process. The world is not black and white. This is not an oil pipeline. It is a telescope to look into the very origins of life in the universe,” he said.

Sonoda-Pale said protesters on the mountain are prepared to demonstrate as they have in the past: in the nonviolent way known as kapu aloha.

“The bottom line is they’re coming up there with weapons. We’re going up there with prayer,” she said.