Any unilateral decision of a Schengen State to apply a temporary travel restriction at its own part of the external borders could be easily undermined by those who would enter the Schengen area at another part of the external borders: likewise a coordinated decision requires the participation of all.
Schengeni riigi ühepoolset otsust kohaldada ajutist reisipiirangut välispiiri oma osal võivad kergesti kahjustada need, kes sisenevad Schengeni alale välispiiri teises osas.