Texas Gov. Greg Abbott is requesting that the federal government reimburse his state more than $11.1 billion for taxpayer money spent on securing the southern border during former President Joe Biden's administration.

Abbott, who sent letters to U.S. Congressional members on Thursday, said the Biden administration's "refusal to do its job the last four years" resulted in the crisis at the southern border that has spilled into the rest of the country.

"President Biden’s policies left Texas and the rest of America defenseless against an unprecedented infiltration of violent criminals, known terrorists, and other hostile foreign actors, like the dangerous Venezuelan gang Tren de Aragua," the governor wrote.

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In response to the federal government's lack of action at the border, Abbott took matters into his own hands and launched Operation Lone Star in March 2021, which deployed the Texas National Guard and Texas Department of Public Safety to the US-Mexico border.

Operation Lone Star has reduced illegal immigration into Texas by 87% over the past four years, proving the "effectiveness of President Donald Trump's border measures," according to Abbott, who added that his efforts have shone a national spotlight on the crisis.

The governor outlined that the operation has also resulted in the apprehension of more than half a million illegal immigrants, stopped more than 140,000 illegal attempts to enter the US, made more than 50,000 criminal arrests, seized more than half a billion lethal doses of fentanyl, built more than 240 miles of border barriers and established the only National Guard base along the Texas-Mexico border.

"In short, Texas stepped up where the federal government refused and in doing so, protected all Americans from President Biden’s dangerous policies," Abbott wrote.

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Though he is proud of the operation, Abbott noted that its success came with a high price tag of more than $11.1 billion, which has been, and continues to be, paid by Texas taxpayers when it "should have been the federal government's responsibility."

In a document breaking down the costs, Abbott said that prior to the Biden administration, the state of Texas spent approximately $800 million every two years to supplement federal efforts at the border.

"The burden that our State has borne is a direct result of a refusal by the federal government to do its job," Abbott wrote. "The work that Texas has done through Operation Lone Star has protected and will continue to benefit the entire country."

House Republicans have introduced bills in the past requesting Texas be reimbursed for the billions spent on border security, but legislation has never been passed.

According to Texas Republican Gov. Greg Abbott, the state’s efforts to crack down on illegal immigration and Tren de Aragua (TdA) migrant gang activity have reduced illegal crossings by nearly 90% and resulted in close to 50,000 criminal arrests.

Abbott’s office said that the Texas-led campaign called "Operation Lonestar," which was first launched in March 2021 and has seen the participation of over a dozen other Republican states, has led to 530,400 illegal immigrant apprehensions and over 49,900 criminal arrests, with more than 42,900 felony charges.

During this operation, Texas also became the first state to build a border wall on its own, continuing border wall construction at strategic points despite President Biden putting a stop to it in the early days of his administration.

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"Our top priority is the safety and security of Texans, including against the growing threat of Tren de Aragua," Abbott said on X. "We will not allow this gang to operate or gain a foothold in Texas."

The governor’s office also said that during Operation Lonestar, Texas law enforcement seized over 620 million lethal doses of fentanyl, which they said is "enough to kill every man, woman, and child in the United States, Mexico, and Canada combined."

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The office noted that Abbott designated TdA, whose violent crime has been sweeping across the nation, a foreign terrorist organization and launched a strike team to target, identify and arrest members of the group.

Texas Department of Public Safety troopers arrested four TdA members crossing the border on New Year's Eve, one of whom was identified as a possible high-ranking member of the gang.

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The statement also said that Texas has transported a total of 119,400 migrants to Washington, D.C., New York City, Chicago, Philadelphia, Denver and Los Angeles, all of which have migrant sanctuary policies in place.

Andrew Mahaleris, a spokesperson for Abbott, told Fox News Digital that Operation Lone Star has cost Texas more than $11 billion, all of which was spent on efforts to secure the border, including deploying thousands of Texas National Guard soldiers and DPS troopers, transporting migrants to sanctuary cities, installing strategic barriers, cracking down against violent gangs like TdA, and building new border wall.

"Because of these efforts, Texas has decreased illegal crossings into the state by 87%," said Mahaleris. "Texas has held the line against the Biden-Harris border crisis for the past four years, and Governor Abbott looks forward to continuing to work closely with President Trump and his incoming administration to protect our state and the nation." 

Texas Gov. Greg Abbott on Monday announced that flags at the state Capitol building in Austin and at all state office buildings will be raised to full-staff next Monday, Jan. 20, to mark President-elect Trump's inauguration.

The move comes despite the official order by President Biden after the Dec. 29 death of former President Jimmy Carter that flags across the country would fly at half-staff for a 30-day mourning period.

Abbott said in his announcement that "on January 20, our great nation will celebrate our democratic tradition of transferring power to a new President by inaugurating the 47th President of the United States, Donald J. Trump. As we unite our country and usher in this new era of leadership, I have ordered all flags to be raised to full-staff at the Texas Capitol and all state buildings for the inauguration of President Trump."

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"While we honor the service of a former President, we must also celebrate the service of an incoming President and the bright future ahead for the United States of America," added the conservative three-term Texas governor.

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An Abbott adviser told Fox News that flags at the Texas Capitol and at state offices would resume flying at half-staff on Jan. 21.

"Texas continues to mourn with our fellow Americans across the country over the passing of former President Jimmy Carter," Abbott said in his statement. "President Carter’s steadfast leadership left a lasting legacy that will be felt for generations to come, which together as a nation we honor by displaying flags at half-staff for 30 days."

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According to the U.S. flag code, U.S. flags are flown at half-staff for a 30-day period to mark the passing of a current or former president, at federal government buildings, military installations and vessels, and at U.S. embassies and other facilities around the world.

Since the U.S. flag code dictates that no flag should fly higher than the American flag on the same or nearby poles, state flags also are lowered during such mourning periods.

Trump earlier this month claimed on social media that "Democrats are all ‘giddy’" about flags being flown at half-staff during his inauguration.

"Nobody wants to see this," Trump argued. "No American can be happy about it. Let’s see how it plays out. MAKE AMERICA GREAT AGAIN!"

The U.S. flag code isn't mandatory, which means that Trump could technically override it once he's inaugurated as president.

The Associated Press observed that a flag at Trump's Mar-a-Lago club in Palm Beach, Florida was flying at full height on Monday.

The flag had been flying at half-staff, but had been raised in the days after Carter's funeral service at National Cathedral in Washington D.C. and burial in his hometown of Plains, Georgia, both of which took place on Thursday.

The Associated Press contributed to this report