President Donald Trump has quietly notified Congress that U.S. hostilities against Iran have resumed, with the White House arguing in a letter to lawmakers that the renewed conflict begins a new 60-day period under the War Powers Resolution, according to Reuters.

The administration contends the new notification is required because the earlier conflict ended with last month's ceasefire and the latest fighting constitutes a separate period of hostilities.

If that legal interpretation prevails, Trump would have another 60 days to continue military operations without additional congressional authorization under the War Powers Resolution.

That interpretation is likely to be challenged, however, with critics expected to argue the renewed fighting is a continuation of the earlier conflict and does not restart the statutory clock.

The notification follows the collapse of the ceasefire after Iran allegedly resumed attacks on commercial shipping in the Strait of Hormuz, according to Reuters.

U.S. forces have since resumed strikes against Iranian military targets as the administration seeks to protect international shipping and pressure Tehran.

The War Powers Resolution generally requires a president to end military hostilities within 60 days unless Congress authorizes the use of force or extends the deadline, although presidents of both parties have long disputed the law's constitutional limits.

The new notification is expected to reignite a constitutional debate on Capitol Hill over the scope of presidential war powers and whether a renewed conflict can trigger a new 60-day period under the law.