In the wake of some questionable changes in Trump's immigration policy, Canada conducted a review of its agreement called the "Safe Third Country agreement" with the U.S.
This agreement between the U.S and Canada is based on the idea that people seeking refuge are required to do so in the first "safe country" where they step foot.
After some review, Canada determined that the U.S. does in fact meet the requirements to be considered a "safe third country."
As a result, any asylum seekers attempting to enter Canada and claim refugee protection via the U.S. will be turned away at the border and sent back to U.S.
In other words, they will be sent back to the first "safe country" from which they came.
Canada has recently received a great deal of pressure, however, to suspend the agreement, especially during the child migrants crisis in the U.S. when children we're being separated from their parents and held in detention facilities.
On the other hand, an influx of irregular migrants has been recorded at Canadian boarders. Just this April an increase of 466% was recorded over easter weekend.
If this trend continues, officials assert that it's a "significant concern for the integrity of our shared boarder."