President Donald Trump and Congress failed to reach an agreement on a spending plan by midnight Friday, triggering a partial shutdown of the federal government. In the past quarter-century, the government has partially shut down three times  -- and far more often in decades past.

U.S. troops will stay at their posts and mail will get delivered, but almost half of the 2 million civilian federal workers will be barred from doing their jobs if the shutdown extends into Monday.

The U.S. military will continue to fight wars and conduct missions around the world, including in Iraq, Syria and Afghanistan. And members of the military will report to work, although they won't get paid until Congress approves funding.

But Defense Secretary Jim Mattis warned Friday that a shutdown will have far-reaching effects.

"Our maintenance activities will probably pretty much shut down," he said during remarks at the Johns Hopkins School of Advanced International Studies. "We do a lot of intelligence operations around the world, and they cost money. Those, obviously, would stop. And I would just tell you that training for almost our entire reserve force will stop."

And, while ships will remain at sea and airstrikes against enemy fighters will continue, any National Guard forces heading out to do weekend training duty around the country will arrive at armories and be told to go home.

Shutdowns have led to...read molre at Military.com