President Trump has directed public attention to a federal statute granting the executive branch sweeping authority over immigration policy, days after announcing comprehensive changes to border enforcement procedures.

In a statement issued Saturday, the president cited Section 212(f) of the Immigration and Nationality Act, legislation that permits the chief executive to suspend entry of non-citizens when such entry is determined to be contrary to national interests.

The statute reads: “Whenever the President finds that the entry of any aliens or of any class of aliens into the United States would be detrimental to the interests of the United States, he may by proclamation, and for such period as he shall deem necessary, suspend the entry of all aliens or any class of aliens as immigrants or nonimmigrants, or impose on the entry of aliens any restrictions he may deem to be appropriate.”

This invocation of presidential authority follows Wednesday’s shooting of two National Guard members in Washington. National Guard member Sarah Beckstrom, age 20, died from injuries sustained in the attack. Fellow guardsman Andrew Wolfe, 24, was also wounded. Authorities have charged Rahmanullah Lakanwal, a 29-year-old Afghan national, in connection with the incident.

The administration’s response has been swift and far-reaching. On Thursday, President Trump announced intentions to halt immigration from what he termed “Third World countries,” reverse admission policies implemented during the previous administration, and remove foreign nationals deemed threats to public safety or incompatible with American values.

The president argued that the nation’s immigration apparatus has been strained beyond its operational capacity and requires time for comprehensive recovery. His proposed measures include terminating federal benefits for non-citizens, reviewing naturalization cases for those accused of threatening domestic stability, and expanding deportation operations.

On Friday, the United States Citizenship and Immigration Services announced an immediate halt to all asylum adjudications, marking a significant shift in immigration processing.

The administration’s actions represent an assertion of executive power that has historical precedent but remains subject to judicial review. Section 212(f) has been invoked by previous administrations, though the scope and application of such authority have occasionally faced legal challenges.

The shooting incident that preceded these announcements has intensified debate over immigration enforcement and national security. The accused shooter’s status as an Afghan national has prompted questions about vetting procedures for refugees and special immigrant visa holders admitted during the withdrawal from Afghanistan.

Immigration enforcement operations have increased substantially in recent days, with agents conducting targeted arrests in multiple cities. The administration maintains these actions focus on individuals with criminal records or outstanding deportation orders.

The policy changes affect multiple categories of immigration, from asylum seekers at the southern border to visa holders already present in the country. The full implementation timeline and specific enforcement mechanisms remain under development.

Legal challenges to these measures are anticipated, as immigration advocacy organizations have indicated their intention to contest what they characterize as overly broad applications of executive authority.

The administration contends these actions are both legally sound and necessary for national security. The coming weeks will likely determine whether courts agree with this interpretation of presidential power under existing immigration law.

Related: Homeland Security Refutes Democratic Claims About Immigration Enforcement