Texas Gov. Greg Abbott for the first time this week chartered a plane to fly migrants from his state to Chicago, marking an escalation after months of having bused migrants to Democratic-run cities to protest President Joe Biden’s border policies.

Abbott, a Republican, acted after Chicago began impounding buses carrying migrants. The city has said it’s enforcing a new ordinance that impounds buses without permits and those that fail to drop off migrants at designated spots.

“Sanctuary city Chicago started obstructing and targeting our busing mission,” Abbott wrote Wednesday on X. “Texas will now expand our operation to include flights to Chicago.

“Until Biden steps up to secure the border, we will continue to provide overwhelmed Texas border towns with much-needed relief,” he added.

The flight from El Paso arrived in Chicago on Tuesday night carrying about 100 people, according to Abbott’s office, which said the passengers signed consent forms available in multiple languages before they departed.

A city of Chicago spokesperson said the flight, which landed at O’Hare International Airport, was chartered by the Texas Department of Emergency Management.

“The City is currently working to find space in the shelter system for all asylum seekers currently staying at O’Hare Airport,” the spokesperson said in a statement.

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The statement added that two unidentified people on the plane “fled” in an Uber vehicle before police arrived.

Abbott, who began relocating migrants more than a year ago, has bused more than 75,500 migrants from Texas to six cities, according to his office.

Officials in those cities have said that buses arrive without warning or coordination and that they have dropped off migrants at random locations. The practice has divided Democrats, with some of them calling on the Biden administration to do more to intervene.

In Chicago, the political clashes over how to care for an influx of tens of thousands of migrants are boiling over, with the city running out of space to care for people who need housing, food and, in some cases, medical attention. Some migrants have slept in police stations and airports until there was space in shelters. This week, a 5-year-old child staying in a temporary shelter in Chicago died, igniting questions about conditions at some of the shelters.

Abbott’s office said it won’t stop transporting migrants to the city, even during winter.

“Governor Abbott launched the border bus mission in April 2022 to provide support to our overrun and overwhelmed border communities as the Biden Administration leaves thousands of migrants in their towns,” spokesman Andrew Mahaleris said in a statement. “Until President Biden steps up and does his job to secure the border, Texas will continue taking historic action to help our local partners respond to this Biden-made crisis.”