President Donald Trump, with a single tweet Wednesday, ramped up tensions with the Kremlin and moved the United States and Russia closer to a military conflict than any time since the Cold War.

Yet most of Washington seemed fixated on other matters — especially Speaker Paul D. Ryan’s announcement that he will not seek re-election and the ensuing race to determine who will lead House Republicans after his departure. Then there was the president’s attack on Deputy Attorney General Rod Rosenstein, who stands between the Oval Office and special counsel Robert S. Mueller III as Trump’s frustration with the ongoing Russia probe intensifies.

Nearly 6,000 miles away, off the coast of Syria and within its borders, the threat of a U.S.-Russia hot conflict loomed large as Trump and Russian President Vladimir Putin — two leaders who thrive on taking big risks, experts warn — engaged in a game of geopolitical chicken.

American and Russian warships traversed the Mediterranean Sea on Wednesday, with Moscow sailing its Syria-based fleet of 11 warships. U.S. combat aircraft moved around the region. And both countries still have sizable numbers of military boots operating on Syrian soil.

Watch: Trump Furor Over Russia Probe Could Blunt Bipartisan Push to Punish Assad

Those moves came after Trump and senior Russian officials traded sharp barbs as the sun rose Wednesday in Washington. Russia’s ambassador to Lebanon warned in a television interview his country would shoot down any U.S. missiles fired into Syria.

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The U.S. commander in chief responded with a tweet: “Get ready Russia, because they will be coming, nice and new and ‘smart!’” (The latter was an apparent reference to technology installed in American weapons to make them more precise.) The tweet marked a curious departure for Trump, who for years has said he will not telegraph his military actions.

He also sent a message directly at Putin, whom he has seldom criticized: “You shouldn’t be partners with a Gas Killing Animal who kills his people and enjoys it!”

Russia vows to shoot down any and all missiles fired at Syria. Get ready Russia, because they will be coming, nice and new and “smart!” You shouldn’t be partners with a Gas Killing Animal who kills his people and enjoys it!

— Donald J. Trump (@realDonaldTrump) April 11, 2018

Dangerous games

Security and foreign policy experts warned Wednesday that the two risk-relishing — and nuclear-armed — leaders are engaged in what one called “a classic game of chicken.”

“A smart strategic planner at the White House would be pushing hard to let the Russians know what we’re going to do,” said Stephen Biddle of the Council on Foreign Relations and George Washington University. “But even then, Russia could put Russians where we say we are going to strike,” essentially daring the United States to send missiles in a direct confrontation. 

Washington and Moscow have tussled rhetorically before, with every recent American president becoming frustrated with Putin. But Biddle noted one big difference amid the current Syria standoff.

“Previous [U.S.] administrations were willing to give a little … and secure the peace,” he said. “Trump just doesn’t seem willing to do that.”

Daniel Davis, a retired Army officer who served in Iraq and Afghanistan, said Trump has two options: one that would be unlikely to convince Syrian President Bashar Assad to give up his chemical weapons, and another that could lead to a U.S.-Russia conflict.

“If you don’t go in heavy, nothing changes vis-à-vis Assad,” said Davis, now with the Defense Priorities think tank. “But if you do go in heavy, the chances for an escalation with Russia goes way up.” The latter action would likely mean targeting Assad’s chemical storehouses, helicopters, artillery and other platforms used in chemical strikes, something Davis said Russia would not allow.

The odds of a U.S.-Russia conflict are real because “the Russians are behaving differently than they have in the past,” Davis said. “In the past, they made generalized threats. But these are sustained, specific, and communicated forcefully by several senior officials.”

Asked if Russia is an enemy of America after its government threatened to shoot down any U.S. missiles headed to Syria, White House Press Secretary Sarah Huckabee Sanders said, “They’ve proven to be a bad actor.”

Experts see the potential for some kind of military conflict because neither Putin nor Trump appears willing to give some ground. What’s more, both have what Biddle called “a gambler’s mentality — they’re both very risk-tolerant.”

[WATCH: Penn. Avenue Report – Lawmakers Want More From Trump in Syria]

Watch: Ryan Announces He Will Not Seek Re-Election

On the sidelines

On Capitol Hill, the jockeying for Ryan’s post — and speculation about it — was already underway Wednesday. Lawmakers were watching for Trump’s Syria move, but doing little more than talking about what they could do.

The U.S. Constitution handed the legislative branch the power to declare war, though modern presidents have acted militarily — especially with one-off operations like Trump’s missile strikes on Syria last April — many times without getting Congress’ approval.

Lawmakers have steadily handed their war powers to the executive branch, and with the courts unwilling to restrain Republican and Democratic presidents’ uses of force, Congress typically does little more than make a lot of noise as American missiles fly.

As the president mulled his next steps, lawmakers fired off tweets and issued statements. There are no plans for votes on measures that would place limits on Trump’s ability to enforce whatever his national security team is planning.

“President Trump has no legal authority for broadening the war in Syria. It is Congress, not the president, who determines whether our country goes to war and Congress must not abdicate that responsibility,” Vermont independent Sen. Bernie Sanders said. “If President Trump believes that expanding the war in Syria will bring stability to the region and protect American interests, he should come to Congress with his ideas.”

Senate Foreign Relations Chairman Bob Corker told reporters he sees no need for the White House to seek congressional approval if the president is planning a repeat of last year’s Syria operation. (Corker has long been a leading proponent of a new authorization measure to legally bless Washington’s Middle East military operations against groups like al-Qaida and the Islamic State.)

“Congress is going to do absolutely nothing,” Davis said. “That is the only certainty here.”

As tensions simmered and lawmakers mostly talked about what they could do, Biddle raised an ominous scenario: If the expected U.S. strikes kill Russians operating there and Putin responds with force, “this could spiral out of control — and quickly.”