Late in 1861, Nonoyama was dispatched to Tsushima han to address an ongoing situation regarding the Russian ship Posadnik, which sought to establish a naval base on Tsushima and refused to leave for the better part of six months. Oguri had attempted to negotiate with the captain of the ship in the fifth month, but was unsuccessful. By the time Nonoyama arrived in the 10th month, the captain had finally been convinced to depart.
Surveying circumstances in Tsushima, Nonoyama determined that the domain's peasants were grossly under-utilizing its agricultural land, using outdated techniques and tools, and that the domain's coastal inhabitants, further, had grossly inadequate boats. Given that the Korea trade on which the domain had long relied was in severe decline, Nonoyama recommended that the domain shift its attentions towards agricultural production.
Domain officials had been petitioning the shogunate at that time to take over responsibility for the island and its defenses, and to transfer the Sô clan to another fief, elsewhere in the realm. Seeing the financial situation of the island, and the logistical difficulties of defending it, Nonoyama reported to the shogunate that administering and defending the island would be too difficult, and recommended that the shogunate not attempt to establish a treaty port there; having the shogunate take over the island, even if the Sô continued to act as liaisons to Korea, would furthermore require difficult re-negotiations with the Korean Court, which counted the Sô clan of Tsushima as its vassals. In 1862/5, acting on Nonoyama's recommendations, the shogunate once again rejected Tsushima's petition.
- Robert Hellyer, Defining Engagement, Harvard University Press (2009), 214-215.