the pioneering work of Presbyterian missionaries who founded them more than a century ago. Currently, the church supports about 215 (70 as of 2021) missionaries abroad annually. Many churches sponsor missionaries abroad at the session level, and these are not included in official statistics. A vital part of the world mission emphasis of the denomination is building and maintaining relationships with Presbyterian, Reformed and other churches around the world, even if this is not usually considered missions. The PC(USA) is a leader in disaster assistance relief and also participates in or relates to work in other countries through ecumenical relationships, in what is usually considered not missions, but deaconship. Ecumenical relationships and full communion partnerships The General Assembly of the Presbyterian Church (USA) determines and approves ecumenical statements, agreements, and maintains correspondence with other Presbyterian and Reformed bodies, other Christians churches, alliances, councils, and consortia. Ecumenical statements and agreements are subject to the ratification of the presbyteries. The following are some of the major ecumenical agreements and partnerships. The church is committed to "engage in bilateral and multilateral dialogues with other churches and traditions in order to remove barriers of misunderstanding and establish common affirmations." As of 2012 it is in dialog with the Episcopal Church, the Moravian Church, the Korean Presbyterian Church in America, the Cumberland Presbyterian Church, the Cumberland Presbyterian Church in America, and the US Conference of Catholic Bishops. It also participates in international dialogues through the World Council of Churches and the World Communion of Reformed Churches. The most recent international dialogues include Pentecostal churches, the Seventh-day Adventist Church, Orthodox Church in America, and others. In 2011 the National Presbyterian Church in Mexico, in 2012 the Mizoram Presbyterian Church and in 2015 the Independent Presbyterian Church of Brazil along with the Evangelical Presbyterian and Reformed Church in Peru severed ties with the PCUSA because of the PCUSA's teaching with regard to homosexuality. National and international ecumenical memberships The Presbyterian Church (USA) is in corresponding partnership with the National Council of Churches, the World Communion of Reformed Churches, and the World Council of Churches. It is a member of Churches for Middle East Peace. Formula of agreement In 1997 the PCUSA and three other churches of Reformation heritage: the Evangelical Lutheran Church in America, the Reformed Church in America and the United Church of Christ, acted on an ecumenical proposal of historic importance, known as A Formula