The State Department approved a deal to sell $330 million in spare aircraft parts to Taiwan this week, marking the second arms deal with Taiwan under the Trump administration.

The spare parts are for the F-16 fighter jet, the C-130 cargo plane, the F-5 fighter jet, and the F-CK-1 Indigenous Defense Fighters (IDF).

“This proposed sale will contribute to the foreign policy and national security of the United States by helping to improve the security and defensive capability of the recipient, which has been and continues to be an important force for political stability, military balance, and economic progress in the region,” the State Department said in a press release.

Taiwan’s Ministry of Foreign Affairs welcomed the approval of the sale in a tweet on Monday, saying that the “decision demonstrates a rock-solid commitment” to the Taiwan Relations Act and the Six Assurances, which underpin the U.S.-Taiwan relationship.

We welcome the #US government’s approval of US$330 million in arms sales to #Taiwan. The decision demonstrates a rock-solid commitment to the #TaiwanRelationsAct & #SixAssurances. It also enables Taiwan to maintain a robust self-defense, as well as cross-strait peace & stability. — 外交部 Ministry of Foreign Affairs, ROC (Taiwan) 🇹🇼 (@MOFA_Taiwan) September 25, 2018

Approval of the sale appeared to be a step towards normalizing arms sales to Taiwan, and a move away from the previous “bundling” method for Taiwan arms sales, according to the U.S.-Taiwan Business Council.

“Notifying each sale when it is ready is a positive development, and indicates more potential activity at the end of this year and into early 2019. It is the approach the Council has advocated for since the original bundling began in 2008,” it said.

The Trump administration has sought to strengthen ties with Taiwan as China has stepped up its diplomatic and military pressure against the self-governing island.

Beijing maintains Taiwan is a renegade province, and not a separate country, despite Chinese nationalists fleeing mainland China and setting up its own government in Taiwan in 1949.

The U.S. provides defense equipment to Taiwan, and maintains robust informal diplomatic relations with Taiwan, which today is a thriving democracy.

China reacted angrily to the sale, urging the U.S. to cancel it and claiming it was a serious violation of international law, the basic norms of international relations, and the three joint communiques between China and the U.S., according to a Chinese news site, China Global Television Network.

Approval from the State Department came days after the Vatican — one of Taiwan’s 17 diplomatic allies — reached a historic deal with China that would give Chinese authorities a say in future Chinese bishops, whose names would be sent to the Vatican for approval. In exchange, the Chinese government would recognize the pope as leader of all Catholics in China.

The deal was criticized by some Catholics as seceding more power to Beijing.

“They’re giving the flock into the mouths of the wolves. It’s an incredible betrayal,” Cardinal Joseph Zen, the former archbishop of Hong Kong, told Reuters last week in opposing the deal.

“The consequences will be tragic and long lasting, not only for the Church in China but for the whole Church because it damages the credibility. Maybe that’s why they might keep the agreement secret,” he said.

Supporters of Taiwan fear that the deal is a potential precursor to the Vatican resuming diplomatic relations with China after 70 years, and a potential ending of ties with Taiwan, since Beijing does not allow countries to have diplomatic relations with both China and Taiwan.