U.S. President Donald Trump has sent a letter to Hungarian Prime Minister Viktor Orban, a long-time ally, which Orban shared today on his Facebook page.

The two leaders met at the White House on November 7, during which Orban said Hungary received a temporary, annual exemption from U.S. sanctions on Russian energy imports. According to the Hungarian prime minister, the exemption helped avert a sharp rise in energy prices that would have significantly affected Hungary’s economy.

In the letter, dated December 10, Trump praised Orban’s bold leadership, describing it as a model for the rest of the world. He also expressed his intention to enhance cooperation between the two countries in the areas of defense, energy, and illegal immigration.

“You have always been unyielding in your defense of the values that make Hungary such an amazing place — faith, family, and national sovereignty,” Trump wrote.

Orban is facing what may be the most serious challenge of his 16-year tenure, amid economic stagnation, rising living costs, and a scandal involving abuse in state-run juvenile detention centers. The controversy has strengthened his main opposition rival, whose party is currently leading in opinion polls. Parliamentary elections are expected to be held in April.

In November, Trump and Orban also discussed various forms of economic assistance. However, last month Trump rejected Orban’s claim that Washington had already agreed to extend $20 billion in financial aid to Hungary. Speaking at a news conference on Monday, Orban acknowledged that Hungary had not secured the level of financial support it initially sought, though talks were continuing on the possibility of a financial safety net.

In his letter, Trump also thanked Orban for the invitation to visit Hungary and said his team would be “in touch” regarding the program. On Monday, Orban said a visit by a “high-ranking” American politician was likely ahead of the election.