The Russians are coming. The Russians are coming — again.

And they’re getting closer.

Twice so far this week a pair of long-range Russian bombers, Tu-95’s capable of carrying nuclear weapons, have flown close to the Alaska coast. The first time they were 100 miles out. The second time about 36 miles. The first time the U.S. scrambled fighter jets to check them out. The second time they just sent up an electronics warfare AWACS plane to monitor their movements and check for other low-flying Russian craft.

There’s actually much more to these flights than meets the eye. For now, it’s all a serious game, despite Secy. of State Rex Tillerson describing relations with Russia now as at a low point.

Russian aircraft and spy ships have cruised along both U.S. coasts, around Japan and Britain. Back in 2015 Russian President Vladimir Putin phoned then President Obama, purportedly to wish him a happy Independence Day. At the same time Russian warplanes were flying within 40 miles of California coastal communities in a kind of fly-by middle finger.

But guess what, the U.S. does the same thing. Most recently U.S. recon patrol and bombers flew over international waters close to China’s disputed man-made islands in the South China Sea.

One goal for all sides, of course, is to make the point, We’re here and we’re watching. The flights are also valuable real-life training opportunities against potential enemies.

The planes can read the other side’s radar, see how far out they are detected, how long it takes for any response to become airborne.

In wartime, such flights over or near enemy territory can be decoys to lull an enemy into complacency. Seventy-four years ago this week, the Army Air Force for several days flew a handful of P-38 Lightnings along the same patrol route over New Guinea in the Pacific. The planes were at the outer limits of their fuel range and their flights seemed predictably random, as intended.

The truth was the U.S. had broken the Japanese code and knew, in advance, that wartime enemy No. 1, Isoroku Yamamoto, would be transiting the area on a certain day. Yamamoto respected Americans well from two diplomatic assignments in Washington and wide travels across the country. As a result, he was an ardent internal opponent of the war against the United States.

A veteran of the Russo-Japanese War where he lost part of one hand, Yamamoto was a major force for modernization and strategic reorganization within the Imperial Navy. He had overall command of the Japanese forces that had so effectively attacked Pearl Harbor in 1941. Afterward he wrote, “I fear all we have done is awaken a sleeping giant and fill him with a terrible resolve.”

Sure enough, as expected on April 18, 1943, the “patrol” of P-38’s spotted two Japanese bombers over New Guinea flying low to avoid detection. They pounced, downing both planes in flames and killing the revered Yamamoto. The loss of such a high-ranking hero was a serious blow to Japanese morale.

But because the U.S. planes had been seen flying around there for several previous days, the Japanese surmised their admiral’s death was just a random wartime encounter. And the code-breaking remained a very useful secret, all because of some seemingly pointless decoy airplane flights.