Taiwan's armed forces are equipped with weapons obtained primarily from the United States. In recent years, however, Taiwan also has procured some weapons from other Western nations and has stressed military "self-reliance," which has resulted in the growth of indigenous military production in certain fields. Taiwan's legislature is currently debating the approval of a special defense budget proposal to purchase defensive systems the U.S. agreed to sell Taiwan in 2001 and earlier. The special budget would provide funds to purchase the Patriot Advanced Capability (PAC-3) missile defense system, P-3C maritime patrol aircraft, and diesel-electric submarines. Taiwan's opposition parties have blocked attempts to pass the special budget on the legislative agenda. These systems would give Taiwan key capabilities in missile defense and anti-submarine warfare to remedy vulnerabilities in countering the P.R.C.'s accelerated military modernization. Taiwan adheres to the principles of the nuclear Non-Proliferation Treaty and has stated that it does not intend to produce nuclear weapons.