U.S. President Donald Trump has threatened to resort to the Insurrection Act, enacted in 1807, to deploy troops in American cities.

Trump stated that he might use the 19th-century law to “suppress rebellions and overcome legal obstacles hindering his decisions to deploy soldiers in U.S. cities.”

Speaking to reporters in the Oval Office, Trump said, “We have the Insurrection Act for a good reason,” noting that the law was introduced in the early 19th century to quell uprisings.

He added, “If I have to invoke it, I will. If people are being killed and courts, governors, or mayors are obstructing us, I’ll do it.”

His remarks came after his attempts to deploy federal forces to suppress protests in several cities were blocked by courts—one court prevented the deployment in Oregon, while another allowed it in Illinois.

Trump has ordered the deployment of federal forces in cities such as Los Angeles and Washington, D.C., and has threatened to send them to other cities as well.

He claimed these measures are necessary to combat crime and protect federal facilities and personnel from protests sparked by his new immigration policies.

In recent days, Trump attempted to send troops to Portland, Oregon, and Chicago, Illinois, but local officials and governors—especially Democrats—argue that such actions are unnecessary and “unconstitutional.”