WASHINGTON, Jul. 10 (Reuters) - A new U.S. air defense base in northern Poland, designed to detect and intercept ballistic missile attacks as part of a broader NATO missile shield, is mission ready, the western military alliance announced on Wednesday.

Speaking on the sidelines of a NATO summit in Washington, the alliance's chief Jens Stoltenberg said the readiness of the base was an important step for transatlantic security in the face of a growing threat posed by ballistic missiles.

"As a defensive alliance we cannot ignore that threat. Missile defense is an essential element for NATO's core task of collective defense," he added, noting ballistic missiles had been widely used in conflicts in Ukraine and the Middle East.

The system, dubbed Aegis Ashore, is based at the northern Polish town of Redzikowo and capable of intercepting short- to intermediate-range ballistic missiles, according to NATO.

The allied missile defense shield is meant to protect European citizens, territory and forces against ballistic missile attacks.

Other key elements of the shield include a second Aegis Ashore site in Romania, along with U.S. navy destroyers based in the Spanish port of Rota and an early-warning radar situated in the Turkish town of Kurecik.

NATO says Aegis Ashore is purely defensive. About 200 military personnel are stationed at the two interceptor sites in Poland and Romania, with the base in the Romanian town of Deveselu operational since 2016.

Photo from Reuters