AUSTIN (KXAN) Members of the Texas National Guard have touched down in Chicago as part of a federal operation. The troops, now under the direction of President Donald Trump, were sent by Gov. Greg Abbott, R-Texas, to protect federal employees.

This comes after Trump deployed federal troops to Washington, D.C., and Los Angeles, in a bid to reduce violent crime.

“[They] need to own up to the fact that they are not doing their job to maintain the safety and security of federal officials who are required to enforce federal law in their city and in their state,” Abbott told Fox News on Tuesday.

‘Trump’s invasion’ lacks historical precedent

Legal experts told affiliate KXAN that while deployments of this nature are common, they’re typically accompanied by either an invitation of the state’s governor. In this case, the Trump administration deploying Texas’s National Guard to Illinois where Gov. J.B. Pritzker, D-Illinois, has actively rejected their presence is unprecedented.

“I am not aware of a situation where the National Guard has been deployed under this statute in another state where that state’s governor has rejected it,” University of Houston Law Center professor Chris Mirasola said.

After Pritzker called the move “Trump’s invasion” on Sunday, Gov. Gavin Newsom, D-California, echoed his sentiment and called for the National Governors Association to condemn the actions.

“STATES CANNOT INVADE ONE ANOTHER,” Newsom wrote on social media. “This is so simple so fundamental to America I cannot believe I have to type those words. America is on the brink of martial law.”

Abbott responded, telling Fox News these reactions are merely ploys for Democrats looking to secure their party’s nomination.

“Pritzker and others have failed to provide security,” Abbott told Fox News Channel’s America Reports on Tuesday. “It doesn’t matter which one of them wins the nomination, because they are utter failures for our country.”

Legal avenues and challenges

Despite the ongoing feuds, one military policy expert said Abbott is within his rights to cede troops over to Trump’s control.

“It’s perfectly appropriate for the governor of Texas to authorize a request that the president of the United States has made,” Katherine Kuzminski, director of studies at the Center for a New American Security, said.

The powers of the president to federalize National Guard members is outlined by Title 10, which allows governors to grant the president authority over state troops. In a ruling last week, U.S. District Court Judge Charles R. Breyer ruled the Trump administration had violated the Posse Comitatus Act which prevents the military from participating in domestic law enforcement when he deployed the National Guard to California earlier this year.

“There is a firm rooting in both U.S. history and tradition, but also in the law against the domestic use of the National Guard or the domestic use of the military for law enforcement purposes,” Kuzminski said.

Instead, these National Guard members are being deployed under Title 32 orders where they report to their Governors but get paid by the federal government.

“The members of the National Guard remain under their state command and control, but they perform a federal mission, which is a very weird kind of a situation,” Mirasola said. “This is a mobilization authority that’s been used a lot in the past, but never in situations where the governor of the state they’re going to be used has so explicitly rejected the use of these National Guard.”

Kuzminski added that governors in the past have refused to accept federal troops, notably during desegregation in the 1950s and 1960s. The key difference is that National Guard troops can still be deployed under Title 10 if a state government is refusing to enforce a federal law, which Kuzminski said right now isn’t the case.

Four cities in five months

“What makes it the most unprecedented is the scope and the scale,” Kuzminski said.

Since the start of June, Trump has deployed the National Guard into Los Angeles, D.C., Memphis and now Chicago. In addition, Trump has ordered troops to Portland, but that move has been temporarily blocked by a federal court order.

Illinois filed a similar suit, though U.S. District Judge April Perry has given the Trump administration until Wednesday night to respond, electing not to immediately halt the deployment of the National Guard.

“Should those federal troops be used to protect federal property, it’s a lot less complicated,” Kuzminski said. “If they are asked to engage in any type of law enforcement, that is when we come against an illegal order under the Posse Comitatus Act. But we might have to live through a gray zone first where troops are receiving orders before it is declared illegal by a court.”