China’s internet for many years provided a wealth of information on the People’s Liberation Army, often showing off new weapons and arms technologies before they were made officially public by the secretive PLA.

Under Chinese President Xi Jinping, however, the amount and quality of disclosures on unofficial military enthusiast websites have declined sharply as China imposes tighter online controls.

Last week, one military website, the Beijing-based Chaoji Da Benying, revealed photos of China’s J-20 stealth jet fighter showing what appear to be knockoffs of two American jet fighter technologies.

An anonymous poster using the online handle “Pingtian” uploaded four photos of a new J-20 in its primer coating, a sign that it was freshly built. The photos revealed two J-20 capabilities deployed on the U.S. front-line fifth-generation stealth jet, the F-35.

The first system shown in the photographs was said to be the J-20’s high-technology distributed aperture system, or DAS.

The Northrup Grumman AN/AAQ-37 DAS for the F-35 is touted by the company as “the only 360-degree, spherical situational awareness,” an electro-optical system that provides protection all around the aircraft and warns pilots of incoming aircraft or missile threats.

Now, apparently, the Chinese have one too. “The camera lens with a relatively large optical aperture in the nose comes with a reddish-purple plating/coating,” the Chinese posting said. “It resembles very much the F-35’s AN/AAQ-37 DAS.”

A second advanced capability for the J-20 revealed by the website is the Universal Water-Activated Release System, or UWARS. The system is a battery-powered, seawater-triggered electro-explosive device used by U.S. Navy and Air Force pilots and manufactured by several American companies.

The system automatically disconnects the parachute canopy from an ejection seat pilot upon immersion in water. The system is designed to prevent pilots who ditch their planes from drowning as a result of their parachutes.

In pointing out the J-20 UWARS, the Chinese poster stated: “Getting our wish fulfilled. Finally see a plane equipped with Universal Water Activated Release System [UWARS]. The improved details show that our J-20 is finally going to reveal its majesty on the open sea.”

China has engaged in massive U.S. technology theft for the past 20 to 30 years, according to U.S. officials. It is not known if the two systems shown on the J-20 were stolen from the United States.

DAVIDSON ON INF

Arms-control proponents have been lamenting President Trump’s decision to jettison the 1987 Intermediate-Range Nuclear Forces (INF) Treaty, despite Moscow’s violation of the accord in building a new intermediate-range cruise missile banned by the pact.

The new commander of the Indo-Pacific Command, Adm. Philip Davidson, however, favors the withdrawal from the treaty and is advocating development of new U.S. INF missiles that can be deployed on land and in mobile launchers. The missiles are needed to counter the growing missile threat from China, he told a recent Capitol Hill hearing.

Under questioning from Sen. Tom Cotton, Arkansas Republican, Adm. Davidson warned about the danger from China’s intermediate-range missiles — those with ranges from 300 miles to 3,400 miles.

“China, since they are not party to the INF Treaty, has been investing in the kind of weapons that create a serious challenge to us,” the four-star admiral told the Senate Armed Services Committee last week.

“Over 95 percent of their ballistic missiles would not be permitted under the INF Treaty,” he added. “For us to have a land-based component with that kind of capability restores maneuver to the force, meaning it will make the air, the maritime and the land component much more viable in any warfare scenario and present a much greater challenge for our adversaries to threaten.”

Mr. Cotton noted that land-based missiles are less expensive and easier to operate than those deployed on ships or aircraft.

“Well, one of the things that will be required, senator, is mobility out of those assets,” Adm. Davidson said. “I think land-based assets will be that way. In this day and age, if it is fixed on the planet it is dead. You don’t even need space assets to support that. The globe has been mapped, and a ballistic missile can find its way there based on its own internal targeting. So we would have to have some mobility in those land-based assets.”

Asked if he thinks the generals of the People’s Liberation Army would be happy to confront U.S. land-based missiles with intermediate ranges, Adm. Davidson said: “No, I think it makes them unhappy.”

NEW CANDIDATE FOR PENTAGON

David H. McCormick, a hedge fund manager and West Point graduate, has emerged as the latest candidate to be the next secretary of defense, sources tell Inside the Ring.

Mr. McCormick is co-chief executive officer of Bridgewater Associates, an investment firm with over $160 billion in assets. He last served in the administration of President George W. Bush as Treasury undersecretary for international affairs.

Mr. McCormick is married to former Trump administration Deputy National Security Adviser Dina Powell and is a friend of Secretary of State Mike Pompeo, who is said to be supporting him for the position, currently held by acting Defense Secretary Patrick M. Shanahan.

Others mentioned for the defense position include Sen. Tom Cotton, Arkansas Republican; retired Army Gen. Jack Keane; and Sen. Lindsey Graham, South Carolina Republican.

Mr. McCormick also is said to have the backing of White House advisers and Trump relatives Jared Kushner and Ivanka Trump.

Little is known about Mr. McCormick’s views on defense and military affairs. His 1998 book, “The Downsized Warrior: America’s Army in Transition,” criticized the scaling-back of America’s largest military service after the demise of the Soviet Union.

The cutbacks undermined morale and threatened the army to its core, he argued.

PUTIN’S NUCLEAR THREAT

Russian President Vladimir Putin issued a threat Wednesday to use nuclear missiles against the United States, including a hypersonic weapon capable of striking rapidly over long distances.

Analysts say it is the first threat of its kind by the Russian leader.

“This is Putin’s first nuclear targeting threat directed specifically against the U.S.,” said Mark Schneider, a former Pentagon nuclear policymaker.

Mr. Putin made the comments in an annual state of the nation address that included criticism of President Trump’s Feb. 1 decision to withdraw from the 1987 Intermediate-Range Nuclear Forces (INF) Treaty, citing Moscow’s deployment of a new ground-launched INF missile called the SSC-8 in violation of the pact.

The treaty banned ground-based missiles with ranges from 300 miles to 3,400 miles.

The Russian leader said that if the United States deploys INF missiles in Europe, “Russia will be forced to create and deploy weapon systems which can be used not only against the territories from which this direct threat would be projected, but also against those territories where decision centers are located, from which an order to use those weapons against us may come.”

One of the new missiles Mr. Putin mentioned is the Avangard hypersonic missile, which can travel at up to 27 times the speed of sound, or 20,000 miles per hour. “It seemed until recently that Russia can’t make a breakthrough in defense technologies, but we made it,” Mr. Putin said of the Avangard, noting that the missile is in production and will be deployed with the first units this year.

Said Mr. Schneider: “There is no indication that the Avangard carries anything other than a nuclear warhead, which Tass says is 2 megatons.”

Additionally, Mr. Putin announced that a military laser weapon called Peresvet will be deployed this year. Other advanced weapons in development include the Sarmat heavy intercontinental ballistic missile, a nuclear-powered cruise missile and a nuclear-armed underwater drone.

• Contact Bill Gertz on Twitter at @BillGertz.