European leaders should be prepared to send military forces to secure any peace deal between of Russia–Ukrainian which will be moderated by the US president-elect Donald TrumpEstonian Foreign Minister Margus Tsahkna said, according to Politico.

While joining NATO would be the best security guarantee for Kiev, Tsahkna said, sending troops to Ukraine to secure a deal could be a second-best solution.

“If we are talking about real security guarantees, that means there will be a just peace and then we are talking about joining NATO”Tsahkna said in an interview with the Financial Times published on Tuesday.

“But without them USA this is impossible. And then we talk about any form of guarantee in the sense of presence on the ground”he added.

During his election campaign, Trump threatened to leave the military alliance if European members did not increase their defense spending. He also promised to bring in a quick peace deal once he takes office in January, prompting fears that the deal will be unfair to Kiev.

Estonia’s foreign minister said he does not believe Trump will actually leave NATO because leaving Europe to Russia is not in the US’s best interest.

But Europeans should boost their defense spending, Tsahkna said, and urged other countries to follow Estonia’s example by raising taxes to finance more defense spending.

Estonia, one of Ukraine’s staunchest supporters, spends 3.4 percent of its GDP on defense, the second highest in NATO after Poland. “We can’t wait for what the US decides”Tsahkna pointed out.