BRUSSELS — Belgium has laid out its red lines for using Russian assets to fund a €140 billion reparations loan to Ukraine, including an agreement by EU countries to share all current and future risks related to the plan for an amount exceeding €170 billion. EU capitals are racing to quell Belgium’s concerns around the loan ahead of a crucial summit of EU leaders on Oct. 23. Securing a political agreement at the summit would pave the way for the bloc to put forward a legal proposal shortly after.