Russia has done this pretty much constantly since 2007, after a lull when the Cold War ended. It makes the news practically every year whenever the weather is good enough for the USAF/RAF/etc. to get some good publicity shots of their shiny new jets flying next to a Russian bomber. (some examples down the years). They seem to send over about 7-8 flights a year.
The US doesn’t seem to do it as much (and funnily enough doesn’t seem to publicise it), but does still send B52’s flying as close as they can to other countries, just to see what they do (eg last year). They will then typically complain about “unsafe interception by Russian fighters”. The US probably also uses it’s RC-135 ‘spy’ planes to gather data, but unsurprisingly there’s no public dinfo on them or their missions.
Basically, Russia does it more, but both sides do it, and as they’re in international airspace, it’s entirely legal. It’s probably partly testing the other country’s air defences (eg ‘how quickly can they get fighters up if we come in from this angle?’), partly training, and partly brinkmanship/sabre rattling. For the aircrews themselves, it’s treated as something of a game, and there’s plenty of stories of crews from different countries waving at each other, taking personal photos, and sometimes holding up porn mags for each other.
While we’re on the subject, the Tu-95 Bear (the Tu-142 is it’s naval cousin) was first flown in 1952, the same year that the B-52 was first flown. Both jets are still flying with their respective air-forces (although both have gone through modernisation programs over the years). When you need to haul a big load of bombs or cruise missiles halfway around the world, 1950’s designs are still good enough.
