The Foreign Ministry said on Wednesday China's defense budget increase is "necessary" and "moderate" as the country faces mounting security pressures and its military is in a critical time of reform.

According to a draft budget report submitted to the National People's Congress for review on Wednesday, China plans to raise its defense budget by 12.2 percent to 808.2 billion yuan ($132 billion) in 2014.

The budget is the first since China's new leadership took office, and marked the biggest increase since a 12.7 percent jump in 2011. The increase was 11.2 percent in 2012 and 10.7 percent in 2013.

Military spending will be used primarily to upgrade the armed forces and improve the living and learning conditions of service personnel, but such spending is still low, both in terms of its share of the GDP and in per capita terms, experts said.

Chen Zhou, a researcher with the Academy of Military Science, said the increasing strategic pressure and high-risk security environment that China is facing require the country to invest more in defense, especially in the development of its navy, air forces and the Second Artillery Force, to secure it and safeguard regional peace.

Chen, who is also a deputy to the National People's Congress, highlighted China's instable peripheral environment, especially the rising maritime security risks, territorial and maritime disputes, as well as terrorist threats.

"The Asia-Pacific region has become a global geopolitical and economic center, with some major powers speeding up strategic adjustments and strengthening military alliances," he said.

While delivering a government report at the opening session of the NPC on Wednesday, Premier Li Keqiang said Beijing will enhance its border, coastal and air defenses and "build China into a maritime power".

NPC deputy Tan Weihong, a senior colonel from the Second Artillery Force, which controls missiles, said China's economic development has enabled its military to catch up, "but regardless where the money is spent or what the military does, other parties that harbor Cold War mentalities will be highly sensitive" to the moves.

On Wednesday, Japan said China's lack of clarity in defense spending is a source of concern for the world and for Japan.

The jump in China's 2014 military budget is something that Japan is keeping an eye on and that Tokyo will discuss with other nations, Japanese Chief Cabinet Secretary Yoshihide Suga told a news conference.

Foreign Ministry spokesman Qin Gang said that both China's development strategies and defense budget are open and transparent, adding there is no need to "make a fuss" about the "moderate" and "reasonable" increase of such a large country given its complicated situation.

"The People's Liberation Army are not Boy Scouts. ... Even if they were, they would grow taller and taller, with bigger feet. You cannot always let them wear small clothes and shoes," he told a regular news conference on Wednesday.

Wang Huayong, political commissar of the East China Sea Fleet, said the military's defensive nature will remain the same both on land and at sea.

"We are out to protect China's economic interests, but we have a long way to go in terms of high-tech military hardware and exercises," he said.

The Chinese military, which started to develop late, also shoulders heavy responsibilities as it is at a stage of intensifying efforts to accomplish the dual historic tasks of military mechanization and full IT application, he added.

Reuters quoted experts as saying that it could be decades before China's military is a match for US armed forces. The US remains the world's biggest defense spender, with a budget of $582.4 billion in 2013, statistics show.

"The efforts to boost the military needs to continue to bring it match the rising global status of China," Wang added. "This also helps China to better shoulder increasing international responsibilities."

China is the largest personnel contributor to UN peacekeeping missions among the five permanent members of the UN Security Council. It also regularly sends naval task forces to conduct escort missions in the Gulf of Aden and off the coast of Somalia.

"Overseas missions cost several times more than those within the country," Chen said. "By moderately raising its defense budget and enhancing its military capabilities, China is also capable of making more contributions to world peace."

Xinhua contributed to this story.