Secretary of Homeland Security John Kelly has issued an order clarifying the status of green card holders under President Trump’s executive order:

BREAKING: DHS Secretary John Kelly says lawful permanent residents from 7 banned countries are now allowed into the U.S. pic.twitter.com/wXWxs08uDN — Eric Geller (@ericgeller) January 29, 2017

Note that nothing has actually changed. Green card holders are still going to be screen upon re-entry to the United States and they will be admitted if there is nothing that indicates they should be denied entry.