Probably not, but not for the reason you are thinking.

No stealthy aircraft is completely invisible to radar. If you get close enough to a sufficiently advanced radar system, it can be detected.

The Northrop B-2 Spirit, the stealthiest active military aircraft in the world.

This is worked around through what is called “Mission Planning”. Known locations of radar systems are mapped out before a mission is started, and the aircraft then flies a route that keeps it far enough from these radar emissions to remain undetected. Throughout the mission, the airwaves are continuously monitored for changes in radar signatures, and if there is new information, the routes are changed while underway.

Keep in mind that an aircraft like the B-2 spirit, which has disciplined shaping to minimize radar returns, best in the world radar absorbing material coatings, top notch maintenance to keep that radar absorbing material intact so it does not degrade to the point where the radar signature grows and – importantly – no vertical stabilizers, is very difficult to detect on radar. Much more so than the likes of the F-22 or F-35.

While some care must be taken to not get too close, it can still get within weapons range of these radar installations undetected in most cases.

So from this perspective, yeah, the B-2 Spirit could theoretically make its way from Russia’s western border in Europe, to the Pacific undetected. It would require serious mission planning, and it wouldn’t be without risk, but it is certainly theoretically possible.

The stealthiness of the aircraft – with a bit of luck and planning – is up to the task.

The distances involved are going to be a problem though.

In order to cross both Russia and China you need to fly quite a long distance. Let’s say we were to leave from an allied air force base in Europe (Ramstein, Germany) and fly to an allied air force base in the Pacific (Kadena, Japan) if you fly in a straight line, that is about 6,050 miles.

But if you fly in a straight line it only takes you over a sliver of Russia just north of the Georgian border. It does take you straight through China though. So, to go over both Russia and China the whole way, we’d need more of an arc, which will increase the distance a bit. I’m guesstimating ~8,800 miles.

But that’s assuming you can just ignore the ground and fly your most ideal route. As previously mentioned, the crew will be changing direction and altitude frequently to minimize exposure to radar installations.

This will lead to a thousands of mile long irregular route, weaving, twisting and turning throughout Russia and China. I don’t even know how to estimate how much this adds to the total route, but I don’t think it is unreasonable to say this is probably at least 10,000 miles.

The problem here is that the max range of the B2 Spirit is 6,900 miles. The U.S. tends to be conservative in its public specs on military hardware, so the true range is probably a little longer, but unlikely long enough for this little trans-eurasian flight in its entirety.

6,900 miles is actually a pretty huge range. Under normal operations it is also not limited to this range. Through the use of airborne refueling it can pretty much stay in the air as long as it needs, limited only by the endurance of its two pilots, their supply of food and water, and – if you go a really long time – eventually the need for maintenance.

Tanker aircraft like the KC-46 Pegasus – however – are based on airliner designs, and are about as stealthy as the broad side of a barn.

The KC-46 Pegasus, based on the Boeing 767.

There is no way a tanker will be able to follow a B2 Spirit throughout Russia and China. It will be very obvious and easy to target.

Luckily this isn’t necessary in pretty much any scenario in a hypothetical conflict with either Russia or China we hope never happens. If wars like these were to break out, the B-2 Spirit, or its replacement the B-21 Raider can reach any target inside Russia or China by either launching from a closer air field or safely conducting an aerial refueling beyond the reach of Russian or Chinese air defenses.

The B-21 Raider intended to slowly replace the B-2 Spirit and other strategic bombers (B-1B Lancer, B-52 Stratofortress) starting in the next year or two and stretching through 2040.

There should never be a reason to overfly all of Russia and China in a B-2 Spirit or any other bomber aircraft.