The siege was incomplete as Morgoth was still capable of sending out various forces of Orcs to weaken the Ñoldor (such as the attack of Hithlum), mainly from the impassable north flanks of the fortress near the unguarded Iron Mountains. The Ñoldor had grown strong enough, however, and these raiding forces posed no significant threat. But these raids enabled Morgoth to coerce people that were captured to his service, which would later prove very disastrous to the Ñoldor and their allies.
However, the Ñoldor and their allies possessed insufficient forces to assault Angband directly. The Siege was broken in the Dagor Bragollach in FA 455.