What role should Congress plan when president orders attack?

WASHINGTON (AP) — The U.S. missile strikes Thursday on a Syrian air base were conducted without formal congressional approval. Some questions and answers about how and why presidents can conduct military action without permission from the 535 representatives of the American people.

Trump did let Congress know of his plans to launch 59 Tomahawk cruise missiles Thursday evening, targeting the air base from which Syrian President Bashar Assad launched a chemical weapons attack earlier this week against his own people, killing more than 80 men, women and children.

A White House official said more than two dozen members of Congress, both Democrats and Republicans, were briefed Thursday by White House and Cabinet officials. House Speaker Paul Ryan, the No. 3 U.S. official, said he was among those informed.

The War Powers Resolution, enacted in 1973, long after American troops began fighting in Vietnam, required the president to consult with Congress before sending U.S. armed forces into combat unless there already had been a declaration of war.

The troops could not stay more than 90 days unless lawmakers backed the decision. The law also sought to give the president "leeway to respond to attacks or other emergencies," according to the Council on Foreign Relations.

And it is that leeway that presidents George W. Bush, Barack Obama and now Trump have used to their advantage. After the Sept. 11 attacks in 2001, Congress gave Bush authority to attack any countries or groups involved in the attacks, which was generally accepted to mean al-Qaida. Obama used that same authority to fight the Islamic State militant group, which emerged in 2014 as an outgrowth of al-Qaida. Trump has used that same authority to continue military action in Iraq, Afghanistan and Syria.

The Obama administration maintained in 2011 that U.S. involvement in the monthslong air campaign against Libya didn't require congressional permission because American forces were largely playing a supporting role as part of an international coalition.