BRUSSELS:  NATO's secretary-general says the US-led alliance has finalized plans for a response force of up to 40,000, twice the current size, and new NATO headquarters offices in Hungary and Slovakia.

The decisions came at a defense ministers' meeting Thursday that was overshadowed by growing concerns over Russia's recent military actions in Syria.

Jens Stoltenberg, the NATO secretary-general, announced the ministers' decisions at a news conference.

"All of this sends a clear message to all NATO citizens. NATO will defend you, NATO is on the ground, NATO is ready," Stoltenberg said.