Trump claims other presidents flouted war powers law. It's a mixed record

President Donald Trump has insisted he doesn't need congressional authorisation to continue the war with Iran, arguing that past US commanders-in-chief didn't seek such approval.

As a critical two-month deadline for the war expired on Friday, Trump said his predecessors considered Congress' authority to limit a president's war powers as "totally unconstitutional".

"So many presidents, as you know, have gone and exceeded it," Trump said when asked if he would seek congressional authorisation.

"It's never been used. It's never been adhered to."

"Nobody's ever asked for it before," Trump added.

The reality is more complicated, however.

Trump is required by a 1973 war powers resolution to "terminate any use of United States Armed Forces" in Iran 60 days after notifying Congress of the start of the war, unless lawmakers vote to continue the conflict.

The legislation was passed to limit the ability of then-President Richard Nixon to continue waging war in Vietnam.

Friday marked the 60th day since 28 February, when the administration notified lawmakers of the strikes against Tehran.

But Trump and Defence Secretary Pete Hegseth contend that the deadline clock paused when the current ceasefire went into effect.

It has sparked a debate about whether or not the truce counts towards the 60-day deadline.

Regardless, some of Trump's recent predecessors sought to comply with war powers authority vested in Congress.

In 1983, President Ronald Reagan received congressional approval to deploy US Marines in Lebanon inside of the 60-day notification window, ensuring the military campaign complied with the law.

President George HW Bush sought congressional authorisation for the 1991 Gulf War before launching Operation Desert Storm, even as he argued that approval from lawmakers wasn't required.

His son, George W Bush, won approval from Congress for wars he waged in Afghanistan (2001) and Iraq (2003).

But Trump is right that other presidents skirted round the war powers law.

Under President Bill Clinton, the 1999 US bombing campaign in Kosovo blew past the 60-day limit without him seeking authorisation from Congress.

The air campaign lasted 78 days.

President Barack Obama argued that the US military campaign in Libya in 2011 did not qualify as "hostilities" under the Nixon-era law, and continued the campaign past the 60-day window without congressional approval.

That Nato-led intervention ended up lasting more than seven months.

David Schultz, a professor of political science and legal studies at Minnesota-based Hamline University, told the BBC: "Just because other presidents haven't invoked it [the 1973 law] doesn't mean that what Trump is doing here is correct."

He added: "Here, Trump has basically committed us to combat without any support from Congress.

"And if we go back to the founding of this country, go back 1776, 1787, one of the fears that our framers had was strong executives committing us to wars without the support of the legislative branch."

Trump has frequently pointed out that the Iran hostilities have been short compared with other conflicts, citing the wars in Vietnam (19 years), Iraq (nearly nine years), World War Two (six years) and Korea (three years).

But with Washington and Tehran still deadlocked over control of the Strait of Hormuz and Iran's nuclear programme, Trump's off-ramp from the conflict is unclear.

As Obama said in 2014 of the US war in Afghanistan: "It's harder to end wars than it is to begin them."