pony up

Japan Times OnlineのAugust 14, 2014の見出しJapan paid \380 million in compensation for accidents by U.S. military personnelの記事の一文を引用します。
Over the past decade, Japan has ponied up a hefty sum to help compensate victims of accidents caused by U.S. military personnel or civilian employees.
"ponied up" は文脈からすると支払った、又は肩代わりしたの意味の様ですが、辞書で確認します。
・Collins Dictionary: to give the money required: That said, better be ready to pony up more cash at the local electronics Mecca.
・Merriam-Webster's Online Dictionary: to pay (money) especially in settlement of an account: despite having good credit, the couple still had to pony up a large down payment for the house