The United States has dramatically increased its military maneuvers across the South China Sea over the past months, prompting angry protests from China and Russia who accuse Washington of fueling unrest in the Asia Pacific region.

Military activity has become the “new normal” in US-Pacific relations and is meant to counter efforts by Beijing and Moscow and show “military superiority” in the increasingly crowded and competitive region, ABC News said in a report on Tuesday.

“We’re for freedom of navigation and following the rules, and to an extent we are pushing back against changing the rules,” said Derek Chollet, a former assistant defense secretary for international affairs.

Admiral John Richardson, chief of US naval operations, said the US’s maritime superiority is being challenged for the first time in 25 years as China and Russia continue to build up their navies. The United States is concerned that China is extending its military reach in the South China Sea by developing man-made islands to accommodate military airfields and weapons systems.

US warships have deliberately sailed close to one of the land formations three times in the past seven months to test China’s territorial claims. Beijing has accused Washington of provocative action and has deployed jets and ships to warn off the US vessels.

Defense Secretary Ashton Carter plans to visit the region next week for an annual Asian national security conference. “China has taken some expansive and unprecedented actions in the South China Sea, pressing excessive maritime claims contrary to international law,” Carter said Friday during a speech to graduates at the US Naval Academy.

China will “pressure” the US over its increased military presence in the Pacific region at the upcoming Strategic and Economic Dialogue in Beijing next week, the official China Daily said on Tuesday.

The South China Sea serves as a crossing for more than $5 trillion worth of annual maritime trade. China claims most of the sea. The Philippines, Vietnam, Malaysia, Taiwan and Brunei have overlapping claims over the waters.