The US strategic position in the Pacific is starting to look a lot like it did 70 years ago — on the eve of Pearl Harbor.

Back in 1941, President Franklin Roosevelt was determined to make an aggressive Asian rival behave — imperial Japan. But he was doing so after a catastrophic reduction in US military strength and readiness.

"China’s generals and admirals have spent the last decade building the means for Assassin’s Mace, an all-out Pearl Harbor-style preemptive strike." --Arthur HermanThat rundown began right after World War I. Then as now, the American public was tired of wars and complicated commitments in faraway places, and the military became a prime object of a cost-conscious Congress.

Two decades of cuts shrank the Army from fourth in the world in 1918 to 19th — right behind tiny Holland — and the Navy from 774 vessels in 1918 to 311 in 1933, with 37 battleships slashed to just 11 by 1933.

No one pushed that policy more than Roosevelt in his first term. “We are not isolationists,” he explained in August 1936, “except as we seek to isolate ourselves from war.” He signed not one but two Neutrality Acts in 1935 and 1936, and telegrammed British Prime Minister Neville Chamberlain after his abject surrender at Munich: “Good man.”

But others interpreted our passivity differently — notably, Japan. Like China today, Japan then saw itself as destined to rule the Western Pacific — and was set on a course of rapid military build-up and modernization. It took America’s retreat (which left outposts like Guam and the Philippines largely undefended) as a green light to start empire-building, with the invasion of China in 1938.

FDR decided it was time to punish Tokyo for its aggression. Japan had extensive trading ties with America (a major source of raw materials). The president terminated our commercial treaty — which the Japanese saw as a direct threat to their economy. Then, in April 1940, he sent the main naval fleet to Pearl Harbor as a show of strength — but the fleet had no clear mission and no way of operating further west, closer to Japan.

In July, he ordered embargoes of scrap iron and aviation fuel to punish Japanese intransigence; in June 1941, he added all oil and steel exports. A month after that, he froze all Japanese assets in America.

In response, Japan decided it would have to seize what it needed to keep its war machine going. Oil-rich Indonesia and rubber-rich Malaya were its targets of priority in December 1941. But the US fleet at Pearl was just strong enough to pose a last remaining obstacle to empire — and just weak enough to seem vulnerable to a sudden, devastating air attack.

The US carriers happened to be at sea when Japan attacked, but the rest of the fleet was devastated: Six battleships sunk and two others were crippled, along with three destroyers, three cruisers and 350 aircraft lost. With 1,200 wounded and 2,400 killed, it was our highest death toll in an unprovoked attack until 9/11.

America was plunged into world war, at a cost in money and lives that dwarfed any of the savings brought by those two decades of defense cuts.

No one is saying another Pearl Harbor is in the offing. But like Japan in 1941, China in 2011 confronts a US policy swinging from apathy to toughness without the military leverage to back it up.

Beijing’s aggressive bullying of neighbors over sovereign rights in the South China Sea, and its steady military buildup, including its navy, deserves presidential attention. But the new militancy from the White House is jarring.

President Obama reassured Asian heads of state in Hawaii last month, “We’re here to stay” — which is supposed to intimidate China into playing nice. Plus, we’re sending troops to Australia to show a “more broadly distributed military presence” in Asia, as Secretary of State Hillary Clinton terms it. Our Navy will step up operations there, too.

Yet that Navy is even smaller than in 1933, with up to 60 more ships destined for retirement with few replacements in sight. And our troops in Australia will number less than 2,500 — just enough to be provocative, but far too small to do anything effective.

Meanwhile, our troops in South Korea and ships and airbases in Japan are more vulnerable than anyone likes to admit. China’s generals and admirals have spent the last decade building the means for Assassin’s Mace, an all-out Pearl Harbor-style preemptive strike, from anti-ship and anti-satellite missiles to a tsunami of cyber attacks that would leave our forces blind and mute around the globe — and render our military presence in Asia a smoldering ruin.

Meanwhile, the Obama administration is determined to act tough. “The future of politics will be decided in Asia,” Secretary Clinton has declared, “and the United States will be right at the center of the action.”

Let’s hope the action isn’t too hot for us to handle.

Arthur Herman is a visiting scholar at AEI.