Some country governments may quietly not be too enthusiastic about the Russian Federation returning the Crimean Peninsula to Ukraine and returning Donbas Region (Donetsk oblast and Luhansk oblast) to Ukraine.   

There might then be pressure upon them to return territories they occupy- square footage in areas whose populations do not want to be occupied.  Some examples:   

Since 1934- United States occupying Guantanamo Bay (Cuba).
Since 1967- State of Israel occupying Golan Heights (Syria).
Since 1967- State of Israel occupying Gaza.
Since 1967- State of Israel occupying West Bank.
Since 1967- State of Israel occupying East Jerusalem.
Since 1974- Turkey occupying Northern Cyprus.
Since 1975- Morocco occupying Western Sahara.
Since 1992- Armenia occupying Nagorno-Karabakh (Azerbaijan).
Since 1992- Russian Federation occupying Transnistria region of Moldova.
Since 2008- Russian Federation occupying Abkhazia & South Ossetia oblasts in Georgia.
Since 2016- Turkey occupying northern portions of Syria.

From United States Navy:  

“Located on the southeast corner of Cuba, Guantanamo Bay’s strategic location and topographic properties have made it a valued possession of maritime powers since the 15th century. Christopher Columbus landed at the Bay on his second voyage to the Americas, and it was later contested by the empires of England, France, and Spain.  In 1898, the Bay was taken by U.S. forces and their Cuban allies for use as a forward-operating base in their effort to wrest Spanish control of the island. In 1903 the United States leased 45 square miles of land and water at Guantanamo Bay, from the newly-independent Cuban government, to be used for fleet sustainment by the growing US Navy. 

A 1934 treaty reaffirming the lease granted Cuba and her trading partners free access through the Bay, modified the lease payment from $2,000 in gold coins per year to the 1934 equivalent value of $4,085 U.S. dollars, and added a requirement that termination of the lease requires the consent of both the U.S. and Cuban governments, or the U.S. abandonment of the base property. [NOTE: Since 1959, the government of the Republic of Cuba has not cashed the yearly check delivered from the United States Department of the Treasury.] 

Base relations with Cuba remained stable and did not significantly change until the Cuban Revolution in the late 1950s, with United States and Cuban relations steadily declining as Revolutionary leader Fidel Castro aligned with the Soviet Union. The United States severed diplomatic ties with Cuba in 1961, and in 1964 Castro cut off water and supply avenues to the base: since then, Naval Station Guantanamo Bay has been self-sufficient, with its own power and water sources.  During its long history the base’s activities have at times included fleet training, ship repair, refueling and resupply, migrant operations, regional humanitarian relief and disaster assistance, search and rescue support, and detention operations. Today it remains the forward, ready, and irreplaceable U.S. sea power platform in the Caribbean, giving decision makers unique options across the range of military and interagency operations.”