The dispute between Japan and Russia is about a group of four islands just north of Japan, that Japan claims are Japanese territory.
The San Francisco Peace treaty, signed by Japan and the allied powers in 1951, stipulated that Japan give up claims to the Kuril Islands between the Russian peninsula of Kamchatka and northern Japan.
But Japan never acknowledged that the four southernmost islands were covered by the agreement, saying they belonged to Hokkaido province.
Putin will never give the islands up, yet he won’t damage the relationship with Japan, experts believe.
“Vladimir Putin understands the importance of diplomacy, he is very subtly handing the Japanese a bone through the idea of joint development,” says Paul Kallender, a research fellow with the Center for Global Security at Keio University in Tokyo.
Issues of sovereignty were very much off the table during the summit, which focused on business deals and trade cooperation.
But it but did result in the creation of a 900-milion-euro fund to invest in joint energy and infrastructure projects over the next five years.
“So, in a sense, Mr Abe's face is saved,” says Kallander. “In the sense that he's got something from the Russians, and from the Japanese side they would like to basically negotiate, under a different set of circumstances later on."
But Kallander thinks this will never happen, as he thinks the Russians have decided that the northern territories are theirs and are ready to work with Japan for joint exploitation of their resources but no more.
One of the countries that is following these developments is China. The relations between Moscow and Beijing have improved a lot since 1989 and they have managed to solve most of their border disputes.
But, says China scholar Michael Dillon, relations were not always that cosy, especially before the collapse of the Soviet Union.
“Russia and China weren't always on good terms," he points out. "After the Sino-Soviet dispute it got to the stage, in 1959, that there was a shooting war at the border and so they were clearly enemies and it took another 20 years before we got back to anything like normal diplomatic relations, even when they were so-called communist countries, they weren't really relating very well to each other."
Trump complicates matters
A complicating factor for diplomacy in the region may be Donald Trump's election as US president. At least for the moment he seems favourable to Russia and Putin seems to return the compliment.
Although it is hard to predict what Trump will do once he is in power, his present stance would indicate a better US-Russia relationship but also, possibly, a militarily more aggressive Japan.
“Trump indirectly even said that it may even be OK if Japan was to arm itself with nuclear weapons,” says Kallander.
At the moment, the researcher says, Japan is capable of going nuclear very quickly, because all the technology is lined up.
This would be very worrying for the Chinese because in the most recent updates of the US-Japan defence alliance, space and cybersecurity cooperation are at the forefront.
So Japan, with the US in the background, is sending signals to China that it is a faithful ally that is making friends with the Russians.
Analysts and diplomats in the countries concerned don’t want to say too much yet.
“We really are in uncharted waters in terms of international diplomacy and east Asia,” says Dillon.
He thinks that all the states involved, whether Japan, Russia or China, are being extremely cautious about making any statements.
But, he says, “the information that we have so far out of the Trump campaign and the tweets that he seems to be addicted to, suggest that there are some very strange and ill-informed ideas on foreign policy, and particular Chinese and Russian sources do not quite know what to make of him.”