The aircraft carriers USS Nimitz, USS Theodore Roosevelt, and USS Ronald Reagan—three of the most powerful warships in the world—have now converged on the western Pacific in a mighty show of force on the eve of President Trump’s 10-day trip to Asia. The three carriers, along with their accompanying cruisers, destroyers, and submarines—all armed with Tomahawk cruise missiles or other advanced munitions—are capable of raining immense destructive force on any nation targeted by the commander in chief. Not since 2007 has there been such a concentration of US firepower in the Asia-Pacific region. There can be only two plausible explanations for this extraordinary naval buildup: to provide Trump with the sort of military extravaganza he seems to enjoy; and/or to prepare for a pre-emptive military strike on North Korea.

First, about the carriers: Normally, the Pentagon stations one carrier and its support group in the western Pacific, with its homeport in Yokosuka, Japan; at present, that vessel is the Ronald Reagan. In addition, the United States has kept one carrier group in the Indian Ocean to provide air support for Army and Marine Corps ground forces in Iraq; until recently that had been the Nimitz. At present, however, the Nimitz has departed the Indian Ocean and is in the Pacific before heading back to its homeport in Washington, while its replacement ship, the Theodore Roosevelt, is also in the Pacific on its way to the Indian Ocean. But for now, all three are massed in the Pacific. The Pentagon says this is a coincidence, but it’s hard to take that seriously.

This convergence is occurring against the backdrop of other developments that all seem to narrow the chances for finding a peaceful outcome to the current standoff between the United States and North Korea. Although the North Koreans have not tested any long-range ballistic missiles or nuclear devices for some six weeks now—very possibly out of a fear of antagonizing China (its sole remaining ally) during the 19th Communist Party Congress (now concluded)—they have shown every indication of doing so again in the future and, indeed, are talking of an above-ground nuclear test.

At the same time, the Trump administration has adopted an even more belligerent stance toward Pyongyang, both through words—largely via the president’s Twitter account—and through military moves. At the United Nations in September, Trump said of North Korean leader Kim Jong-un, “Rocket Man is on a suicide mission for himself and for his regime,” warning that if the North attacked the United States or its allies, “we will have no choice but to totally destroy North Korea.” When North Korean Foreign Minister Ri Yong-ho condemned Trump’s words, the president retorted, via Twitter, “If he echoes thoughts of Little Rocket Man, they won’t be around much longer!”

Although Trump spoke at the UN in terms of defensive action, his statements have on occasion hinted at a willingness to employ force in an offensive manner, to destroy North Korean rockets before they are launched or to destroy larger elements of the regime’s military and governing capacity. “Presidents and their administrations have been talking to North Korea for 25 years, agreements made and massive amounts of money paid…hasn’t worked, agreements violated before the ink was dry, makings fools of U.S. negotiators,” he tweeted on October 7, referring to past US efforts to negotiate the denuclearization of the North. “Sorry, but only one thing will work!” Asked later that day to explain what he meant by that, Trump told reporters, “You’ll figure that out pretty soon.”

Trump’s threats to use military force against the Kim regime have repeatedly been cast into doubt by senior US military officials, who insist that any such action would inevitably trigger North Korean retaliation, in all likelihood leading to massive civilian casualties—certainly in the tens of thousands, quite possibly in much greater numbers. How far Pyongyang has progressed in its attempts to install nuclear warheads on its ballistic missiles is unknown, but it is widely believed capable of launching chemical weapons and conventionally armed missiles against South Korea and Japan, along with devastating barrages of artillery fire. The North Koreans have deployed thousands of long-range artillery pieces and multiple-rocket launchers in hardened positions just north of the demilitarized zone, many of which are thought capable of striking Seoul, the South’s capital and largest city, located just 30 miles south of the DMZ. “The bottom line is it would be a catastrophic war if this turns into a combat,” said Defense Secretary James Mattis last May.

Despite such cautioning, and much talk in the media about the likely death toll from a such clash, President Trump and his top aides appear to be planning for just such an encounter—and the Pentagon is falling in step behind them. On October 10, the White House released a little-noticed statement by the press secretary on the outcome of a meeting between Trump and his national-security team, saying “the briefing and discussion focused on a range of options to respond to any form of North Korean aggression or, if necessary, to prevent North Korea from threatening the United States and its allies with nuclear weapons”—a clear reference to preemptive attacks.

A further hint of such action came in testimony by Secretary Mattis and Secretary of State Rex Tillerson before the Senate Foreign Relations Committee on October 30. Asked by Senator Ben Cardin whether President Trump has congressional authorization to employ military force against North Korea, Tillerson said no, but then added, “[If] there’s an imminent threat against the United States, he has certain powers [to act].” In subsequent questioning by Senator Chris Murphy, Mattis said that he could imagine a scenario in which Trump ordered an attack on North Korea without consulting Congress, akin to the April 6 missile strike on the Syrian air base at Shayrat (supposedly intended to degrade Syria’s chemical-weapons capabilities) in response to the sarin gas attack on Khan Sheikhoun by Syrian government forces. Asked whether the mere possession of a nuclear weapon by the North could be considered an “imminent” threat, both Mattis and Tillerson declined to answer, saying it would depend on the circumstances.