[Reuters Analysis] Nuclear curveball: Trump's testing plan raises fears, confusion in Washington

• Trump says he told Pentagon to start testing nuclear weapons, but details unclear
• Experts say explosion tests would be disruptive
• Breaking the moratorium on nuclear tests could benefit US adversaries

By Phil Stewart, Idrees Ali, David Brunnstrom and Simon Lewis

WASHINGTON, Oct 30 (Reuters) - If U.S. Navy Vice Admiral Richard Correll thought he was going to have an easy confirmation hearing on Thursday to become the commander of America's nuclear forces, those hopes surely vanished at 9:04 p.m. the night before he was to testify.

That was when President Donald Trump shocked the world by announcing on social media that he had asked the U.S. military to "start testing our Nuclear Weapons", saying the United States could not fall behind Russia and China.

"Russia is second, and China is a distant third, but will be even within 5 years," Trump said.

During a roughly 90-minute hearing on Thursday morning at the Senate Armed Services Committee, Correll faced repeated questions about Trump's comments from puzzled U.S. lawmakers, embodying the confusion that the Republican president unleashed in Washington and beyond.

The top Democrat on the committee, Senator Jack Reed, asked Correll whether a resumption of U.S. nuclear explosive testing would be destabilizing, triggering a global nuclear arms race.

"If confirmed as the commander of STRATCOM, my role would be to provide military advice on any discussions on the way ahead with respect to testing," Correll said.

The vice admiral, who Trump nominated in early September to lead the U.S. military's Strategic Command, or STRATCOM, which focuses on nuclear deterrence and strike capabilities, kept answering questions carefully throughout the hearing.

At one point, Senator Angus King, an independent, asked whether Trump's post could be about testing delivery systems such as missiles rather than explosive testing of nuclear devices.

"I don't have insight into the President's intent. I agree that could be an interpretation," Correll said.

U.S. MORATORIUM

U.S. officials on Thursday did not clarify whether Trump was calling for testing of nuclear weapon delivery systems or ending a 33-year moratorium on explosion tests, which experts said would be disruptive and carry the risk of provoking escalation from rivals, evoking anxious memories of the Cold War.

Vice President JD Vance said testing was part of ensuring the U.S. nuclear arsenal functions properly.

The U.S. and other nuclear powers have long stopped detonating actual nuclear warheads and instead use advanced computer simulations to maintain the readiness of their arsenals.

"There is no good reason for the United States to resume explosive nuclear testing - it would actually make everyone in the U.S. less safe," said Tara Drozdenko, director of the global security program at Union of Concerned Scientists.

"The U.S. has so much to lose and so little to gain from resuming testing," she said.

SENDING A MESSAGE TO MOSCOW AND BEIJING

Many analysts said that Trump, who often tries to project strength as a negotiation tactic, likely was seeking to send a message to Moscow and Beijing.

In his social media post issued ahead of his meeting with Chinese President Xi Jinping in South Korea, the president said he had instructed the Pentagon to start testing "on an equal basis" and added, "That process will start immediately."

Only North Korea has conducted a nuclear test explosion in this century, the last in 2017.

Russia, which has tested two new nuclear-powered weapons in recent days, has been accused by Washington of conducting so-called low-yield tests and of lacking transparency in its nuclear program, but has not conducted a full-scale nuclear explosion.

Russian President Vladimir Putin had cautioned that if any country tested a nuclear weapon, then Moscow would too, a Kremlin spokesperson said on Thursday.

China has repeatedly rebuffed efforts across U.S. administrations to hold talks on nuclear arms. While Beijing is undertaking efforts to dramatically increase its nuclear weapons stockpiles it has expressed little interest in negotiating with Russia and the U.S., arguing those countries’ nuclear forces are currently considerably larger.

"If the goal is to generate leverage to force China to negotiate, I think that's unlikely to work," said James Acton, co-director of the nuclear policy program at the Carnegie Endowment for International Peace.

China hopes the U.S. will abide by its commitment to a moratorium on nuclear testing and obligations under a test ban treaty, Beijing's foreign ministry said on Thursday.

BENEFITING U.S. ADVERSARIES

Breaking the moratorium on U.S. nuclear tests could benefit Washington's nuclear rivals by allowing them to conduct more tests, said Ploughshares, a foundation focused on reducing nuclear threats.

The United States has conducted the majority of all nuclear test explosions and retains data gathered from its 1,030 tests since 1945.

STRATCOM, where Correll is the current No. 2, had just certified the U.S. military's nuclear arsenal in January.

"A return to testing will benefit U.S. adversaries by allowing them to catch up in nuclear research and weapons development," Ploughshares said in a statement.

A source at the Department of Energy, who spoke on condition of anonymity, said any test would take place deep underground at a Nevada site, which is mandated to be ready to conduct tests within 36 months.

At the hearing, Senator Jacky Rosen said her home state of Nevada had suffered from being the site of U.S. nuclear explosive tests from 1951 to 1992, and vowed to prevent Trump from resuming them: "I'm going to be crystal clear: I will not let this happen. Not on my watch."