A bipartisan group of U.S. policy experts recommended Wednesday that Japan's Self-Defense Forces and the U.S. military create a combined joint task force to better cope with possible contingencies with China over Taiwan, as well as the South and East China seas, as part of an effort to strengthen the bilateral alliance.

Aside from the launch of such a task force, the study group suggested in a report titled "More Important than Ever -- Renewing the U.S.-Japan Alliance for the 21st Century" that Tokyo and Washington expand joint and combined use of bases in Japan and engage in more structured joint operations planning in the face of China's regional assertiveness and North Korea's nuclear and missile threats.

Chaired by former Deputy Secretary of State Richard Armitage and Joseph Nye, a former assistant secretary of defense for international security affairs, the group under the nonprofit Center for Strategic and International Studies urged Prime Minister Shinzo Abe's government to spend "more than 1 percent" of Japan's gross domestic product on defense.

The report, which contains a set of policy recommendations to boost the Japan-U.S. alliance, is the fourth of its kind, following ones released in 2000, 2007 and 2012.

The policy experts criticized President Donald Trump's "America First" security and trade policies, saying his "protectionist policies and questioning of the value of forward U.S. military presence pose a serious risk to the alliance."

"While the United States and Japan debate 20th-century tariffs, the 21st-century threats to regional security and prosperity -- particularly from China and North Korea -- are growing," the report said. "Cracks are starting to show in the alliance."

Trump's "transactional approach to alliances" and "unconditional engagement of authoritarian leaders" such as North Korean leader Kim Jong Un have "undermined perceptions of U.S. support for shared values, including human rights, democracy, free markets and trade, and the rule of law," it said.

While pointing to uncertainties about the future of the alliance, the report called for Japan's participation in a proposed combined joint task force as a way of reducing "a major burden" the commander of the U.S. Indo-Pacific Command assumes not only directing the warfight but managing relations with Washington and liaising with allied forces.

"If the United States and Japan are to operate more effectively together in a crisis, they should create a combined joint task force for the western Pacific," it said.

The report also urged Tokyo and Washington to speed up allied decision making via combined contingency planning, especially when Beijing often relies on "fait accompli tactics," which take advantage of slow decision-making cycles by other parties.

"To deepen cooperation, Japan should embed officers from the Self-Defense Forces within relevant U.S. units, including the planning staff of the Indo-Pacific Command," it said.

Moreover, the report recommended the inclusion of Japan in the Five Eyes intelligence sharing network with the United States, Britain, Australia, Canada and New Zealand.

On the economic front, the report suggested Japan and the United States set up a regional infrastructure fund to counter China's growing clout throughout the Indo-Pacific region with President Xi Jinping's multibillion-dollar "One Belt, One Road" cross-border infrastructure initiative.

"China's investment in regional infrastructure is often welcome, but the coercive political and economic leverage it is creating -- and sometime using -- is not," it said. "The U.S.-Japan alliance must demonstrate that it can present an attractive alternative."