BRUSSELS (AP) — Turkey's invasion of northern Syria — along with the criticism and threats of sanctions brandished by fellow NATO members at Ankara over the offensive — is close to sparking a crisis at the world's biggest military alliance.

But despite the high political-military tensions, Turkey is very unlikely to be ejected from the 29-member alliance, for NATO has seen tense times and survived them before.

From the Suez Canal crisis in 1956 to France leaving its military command structure in 1967 — which forced the alliance to move its headquarters to Brussels in Belgium — to the deep split among allies over the Iraq war in 2003, NATO bonds have been tested. But no country has left the alliance or been forced out.