NATO will increase the size of its rapid reaction force by almost eight times to 300,000 in response to the era of strategic rivalry, said NATO Secretary General Jens Stoltenberg, AP reported.

The NATO Response Force currently has around 40,000 troops, which can be quickly deployed if needed.

Combined with other measures, including deploying forces to protect specific allies, the move is part of "the biggest reform of collective defense and deterrence since the Cold War," Stoltenberg said at a press conference ahead of this week's NATO summit in Madrid.

Stoltenberg expects allies to make it clear that they consider Russia the most serious and direct threat to our security.

NATO's new strategic concept also expects the alliance to address China's security concerns for the first time, he said. In Madrid, the allies will discuss how to respond to the growing influence of Russia and China.

Allies will agree to provide additional military support to Ukraine during the summit, and NATO members intend to adopt a strengthened comprehensive assistance package, including the supply of secure communications systems and defense against drones.

In the long term, the Allies aim to help Ukraine transition from Soviet-era weapons to modern NATO equipment, Stoltenberg said.

Another central theme of the NATO summit will be the possibility of Finland and Sweden joining the alliance.

Stoltenberg said that Turkish President Recep Tayyip Erdogan, Finnish President Sauli Niinistö and Swedish Prime Minister Magdalena Andersson agreed to meet on the sidelines of the summit.