The North Atlantic Treaty Organization on Wednesday defined China as a challenge for the first time in its updated guidelines, while also singling out the increasing threat from Russia as the post-Cold War peace in Europe has been shattered by the war against Ukraine.

NATO issued the new Strategic Concept during its summit in Madrid, marking the first update since 2010 of the document that typically spans about a decade. It says that threats are now "global and interconnected" and developments in the Indo-Pacific, where Beijing is increasing its military and economic clout, could affect Euro-Atlantic security.

While declining to call China an "adversary," Secretary General Jens Stoltenberg, speaking after the paper was endorsed, called for being "clear-eyed about the serious challenges" the Asian economic powerhouse represents through its assertiveness, coercive policies and deepening partnership with Moscow.

The previous Strategic Concept was drawn up around a period when NATO was focused on Afghanistan, after the Sept. 11 terror attacks on U.S. soil in 2001. At that time, the document described the Euro-Atlantic area as being "at peace" and even sought a "strategic partnership" between NATO and Russia, while China was not mentioned at all.

In a stark contrast, the latest document depicts Russia as "the most significant and direct threat" to the allies' security. It also lists a range of behaviors by China deemed concerning, such as the use of its "political, economic and military tools to increase its global footprint and project power, while remaining opaque about its strategy, intentions and military build-up."

China also seeks to control critical infrastructure and supply chains, and strives to subvert the rules-based international order, including in the space, cyber and maritime domains, NATO said.

"We will work together responsibly, as allies, to address the systemic challenges posed by the PRC to Euro-Atlantic security," the document said, referring to the acronym of the People's Republic of China, the country's official name. It also warns of the "mutually reinforcing attempts to undercut the rules-based international order" by China and Russia.

The Indo-Pacific is "important" for the trans-Atlantic alliance, it acknowledges in the document, and vows to strengthen dialogue and cooperation with new and existing partners in the region to tackle "cross-regional challenges and shared security interests."

NATO gave the green light to the latest guidelines during the first day of its two-day summit in the Spanish capital, which Stoltenberg hailed as a "historic and transformative" meeting for the bloc facing "the most serious security crisis" since World War II.

In a sign of deepening linkage between the security in Europe and the Indo-Pacific, leaders from Japan, South Korea, Australia and New Zealand, which NATO views as its Asia-Pacific partner countries, attended the summit for the first time.

The Brussels-based, 30-member alliance also decided the same day to accept Finland and Sweden as members, after the two Nordic countries made a historic decision to end their longstanding military nonalignment policies in the wake of Russia's war.

NATO was created in 1949 by the United States, Canada and several Western European nations to defend against the threat from the Soviet Union and its Eastern European satellites.

But the end of the Cold War in 1991 led to Europe spending less on defense, and its nations ventured outside the continent in order to address the threat from terrorism.

Russia's annexation of Crimea from Ukraine in 2014 prompted the alliance to renew its focus on defense and deterrence against Moscow. In the wake of the Ukraine invasion that began in February, more troops have been deployed along NATO's eastern flank.

As part of what it calls a "fundamental shift" in its defense, NATO said it will boost the number of troops on high alert to well over 300,000, up from the 40,000 under its direct command in the eastern part of the alliance closer to Russia.

The United States announced it will enhance its military presence in Europe and that it will continue to adjust its force posture based on the "threat."

While the total number of American troops in Europe has been raised by over 20,000 to more than 100,000 in response to the Ukraine crisis, the U.S. government said it is working with Spain to increase the number of U.S. naval destroyers stationed at Rota naval base, known as the "gateway to the Mediterranean," from four to six.

The United States is also planning to send two additional F-35 fighter jet squadrons to Britain and station additional air defense and other capabilities in Germany. It will also establish a permanent Army garrison headquarters in Poland.